diff --git a/pkg/event/event.go b/pkg/event/event.go
index a68944c3..e0af1ba8 100644
--- a/pkg/event/event.go
+++ b/pkg/event/event.go
@@ -20,4 +20,5 @@ const (
 	RestartDeployment    = "RestartDeployment"
 
 	WarningHittingHardMaxReplicaLimit = "HitHardMaxReplicaLimit"
+	WarningReplicaValidation          = "ReplicaValidationWarning"
 )
diff --git a/pkg/hpa/service.go b/pkg/hpa/service.go
index 099a00a1..e9e43b8c 100644
--- a/pkg/hpa/service.go
+++ b/pkg/hpa/service.go
@@ -412,24 +412,44 @@ func (c *Service) ChangeHPAFromTortoiseRecommendation(tortoise *autoscalingv1bet
 		return nil, tortoise, fmt.Errorf("get maxReplicas recommendation: %w", err)
 	}
 
+	// Apply user-specified maxReplicas limit if set
 	if tortoise.Spec.MaxReplicas != nil && recommendMax > *tortoise.Spec.MaxReplicas {
 		recommendMax = *tortoise.Spec.MaxReplicas
 	}
 
+	// Apply cluster-wide maxReplicas limit
 	if recommendMax > c.maximumMaxReplica {
 		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningHittingHardMaxReplicaLimit, fmt.Sprintf("MaxReplica (%v) suggested from Tortoise (%s/%s) hits a cluster-wide maximum replica number (%v). It wouldn't be a problem until the replica number actually grows to %v though, you may want to reach out to your cluster admin.", recommendMax, tortoise.Namespace, tortoise.Name, c.maximumMaxReplica, c.maximumMaxReplica))
 		recommendMax = c.maximumMaxReplica
 	}
 
-	hpa.Spec.MaxReplicas = recommendMax
+	// Ensure maxReplicas is at least minimumMinReplicas
+	if recommendMax < c.minimumMinReplicas {
+		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation, fmt.Sprintf("MaxReplica (%v) is below minimum allowed replicas (%v), adjusting to minimum", recommendMax, c.minimumMinReplicas))
+		recommendMax = c.minimumMinReplicas
+	}
 
 	recommendMin, err := GetReplicasRecommendation(tortoise.Status.Recommendations.Horizontal.MinReplicas, now)
 	if err != nil {
 		return nil, tortoise, fmt.Errorf("get minReplicas recommendation: %w", err)
 	}
+
+	// Apply cluster-wide minReplicas limit
 	if recommendMin > c.maximumMinReplica {
+		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation, fmt.Sprintf("MinReplica (%v) suggested from Tortoise (%s/%s) hits a cluster-wide maximum min replica number (%v), capping to maximum", recommendMin, tortoise.Namespace, tortoise.Name, c.maximumMinReplica))
 		recommendMin = c.maximumMinReplica
-		// We don't change the maxReplica because it's dangerous to limit.
+	}
+
+	// Ensure minReplicas is at least minimumMinReplicas
+	if recommendMin < c.minimumMinReplicas {
+		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation, fmt.Sprintf("MinReplica (%v) is below minimum allowed replicas (%v), adjusting to minimum", recommendMin, c.minimumMinReplicas))
+		recommendMin = c.minimumMinReplicas
+	}
+
+	// Ensure minReplicas doesn't exceed maxReplicas
+	if recommendMin > recommendMax {
+		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation, fmt.Sprintf("MinReplica (%v) exceeds MaxReplica (%v), adjusting MaxReplica to MinReplica", recommendMin, recommendMax))
+		recommendMax = recommendMin
 	}
 
 	if recordMetrics {
@@ -459,6 +479,31 @@ func (c *Service) ChangeHPAFromTortoiseRecommendation(tortoise *autoscalingv1bet
 		minToActuallyApply = recommendMin
 	}
 
+	// Final validation: Ensure minReplicas doesn't exceed maxReplicas after phase-specific adjustments
+	if minToActuallyApply > recommendMax {
+		if tortoise.Status.TortoisePhase == autoscalingv1beta3.TortoisePhaseBackToNormal {
+			// During BackToNormal, temporarily increase maxReplicas to allow safe gradual reduction
+			// This preserves the safety mechanism while ensuring HPA validity
+			originalMaxReplicas := recommendMax
+			recommendMax = minToActuallyApply
+			c.recorder.Event(tortoise, corev1.EventTypeNormal, event.Working,
+				fmt.Sprintf("Temporarily increased MaxReplicas from %v to %v during BackToNormal phase to allow safe gradual MinReplicas reduction",
+					originalMaxReplicas, minToActuallyApply))
+		} else {
+			// For other phases, cap minReplicas to maxReplicas
+			minToActuallyApply = recommendMax
+			c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation,
+				fmt.Sprintf("MinReplicas was capped to MaxReplicas (%v) to prevent HPA validation error", recommendMax))
+		}
+	}
+
+	// Ensure final minReplicas is at least minimumMinReplicas
+	if minToActuallyApply < c.minimumMinReplicas {
+		c.recorder.Event(tortoise, corev1.EventTypeWarning, event.WarningReplicaValidation, fmt.Sprintf("Final MinReplicas (%v) is below minimum allowed replicas (%v), adjusting to minimum", minToActuallyApply, c.minimumMinReplicas))
+		minToActuallyApply = c.minimumMinReplicas
+	}
+
+	hpa.Spec.MaxReplicas = recommendMax
 	hpa.Spec.MinReplicas = &minToActuallyApply
 	if tortoise.Spec.UpdateMode != autoscalingv1beta3.UpdateModeOff && recordMetrics {
 		// We don't want to record applied* metric when UpdateMode is Off.
diff --git a/pkg/hpa/service_test.go b/pkg/hpa/service_test.go
index e6a02298..364b02ba 100644
--- a/pkg/hpa/service_test.go
+++ b/pkg/hpa/service_test.go
@@ -2746,6 +2746,983 @@ func TestClient_UpdateHPAFromTortoiseRecommendation(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "MinReplicas below minimum allowed replicas should be adjusted",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseWorking,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     10,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     1, // Below minimum (3)
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(3), // Should be adjusted to minimum
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "MaxReplicas below minimum allowed replicas should be adjusted",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseWorking,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     1, // Below minimum (3)
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     3,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 3, // Should be adjusted to minimum (3) since minReplicas is 3
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "MinReplicas exceeds MaxReplicas should adjust MaxReplicas",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseWorking,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     5,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     8, // Exceeds maxReplicas (5)
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(8),
+					MaxReplicas: 8, // Should be adjusted to minReplicas (8)
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "BackToNormal phase should temporarily increase MaxReplicas for safety",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseBackToNormal,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     5,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     3,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(10), // Current min is high (from emergency)
+					MaxReplicas: 5,            // But max is low
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(9), // Reduced by 0.95 factor (10 * 0.95 = 9.5, truncated to 9)
+					MaxReplicas: 9,           // Temporarily increased to accommodate minReplicas
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "Emergency phase should set minReplicas to maxReplicas",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseEmergency,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     10,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     3,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(10), // Should be set to maxReplicas in emergency
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "User-specified MaxReplicas limit should be respected",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode:  v1beta3.UpdateModeAuto,
+						MaxReplicas: ptr.To[int32](5), // User-specified limit
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseWorking,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     10, // Exceeds user-specified limit (5)
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     3,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 5, // Should be capped to user-specified limit
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "MinReplicas above cluster-wide maximum should be capped",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseWorking,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     10,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     1000, // Above cluster-wide maximum (1000)
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(3),
+					MaxReplicas: 10,
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(1000), // Should be capped to cluster-wide maximum
+					MaxReplicas: 1000,           // Should also be adjusted to match
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "Final validation should ensure minReplicas doesn't exceed maxReplicas after BackToNormal",
+			args: args{
+				ctx: context.Background(),
+				tortoise: &v1beta3.Tortoise{
+					Spec: v1beta3.TortoiseSpec{
+						UpdateMode: v1beta3.UpdateModeAuto,
+					},
+					Status: v1beta3.TortoiseStatus{
+						TortoisePhase: v1beta3.TortoisePhaseBackToNormal,
+						AutoscalingPolicy: []v1beta3.ContainerAutoscalingPolicy{
+							{
+								ContainerName: "app",
+								Policy: map[v1.ResourceName]v1beta3.AutoscalingType{
+									v1.ResourceMemory: v1beta3.AutoscalingTypeHorizontal,
+								},
+							},
+						},
+						Conditions: v1beta3.Conditions{
+							TortoiseConditions: []v1beta3.TortoiseCondition{
+								{
+									Type:               v1beta3.TortoiseConditionTypeHPATargetUtilizationUpdated,
+									Status:             v1.ConditionTrue,
+									LastUpdateTime:     metav1.NewTime(now.Add(-3 * time.Hour)),
+									LastTransitionTime: metav1.NewTime(now.Add(-3 * time.Hour)),
+									Reason:             "HPATargetUtilizationUpdated",
+									Message:            "HPA target utilization is updated",
+								},
+							},
+						},
+						ContainerResourcePhases: []v1beta3.ContainerResourcePhases{
+							{
+								ContainerName: "app",
+								ResourcePhases: map[v1.ResourceName]v1beta3.ResourcePhase{
+									v1.ResourceMemory: {
+										Phase: v1beta3.ContainerResourcePhaseWorking,
+									},
+								},
+							},
+						},
+						Targets: v1beta3.TargetsStatus{
+							HorizontalPodAutoscaler: "hpa",
+						},
+						Recommendations: v1beta3.Recommendations{
+							Horizontal: v1beta3.HorizontalRecommendations{
+								TargetUtilizations: []v1beta3.HPATargetUtilizationRecommendationPerContainer{
+									{
+										ContainerName: "app",
+										TargetUtilization: map[v1.ResourceName]int32{
+											v1.ResourceMemory: 90,
+										},
+									},
+								},
+								MaxReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     5,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+								MinReplicas: []v1beta3.ReplicasRecommendation{
+									{
+										From:      0,
+										To:        2,
+										Value:     3,
+										UpdatedAt: now,
+										WeekDay:   ptr.To(now.Weekday().String()),
+									},
+								},
+							},
+						},
+					},
+				},
+				now: now.Time,
+			},
+			initialHPA: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					MinReplicas: ptrInt32(20), // Very high current min (from emergency)
+					MaxReplicas: 5,            // But max is low
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](60),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			want: &v2.HorizontalPodAutoscaler{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "hpa",
+				},
+				Spec: v2.HorizontalPodAutoscalerSpec{
+					Behavior:    defaultHPABehaviorValue.DeepCopy(),
+					MinReplicas: ptrInt32(19), // Reduced by 0.95 factor (20 * 0.95 = 19)
+					MaxReplicas: 19,           // Temporarily increased to accommodate minReplicas
+					Metrics: []v2.MetricSpec{
+						{
+							Type: v2.ContainerResourceMetricSourceType,
+							ContainerResource: &v2.ContainerResourceMetricSource{
+								Name: v1.ResourceMemory,
+								Target: v2.MetricTarget{
+									AverageUtilization: ptr.To[int32](90),
+								},
+								Container: "app",
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
 	}
 
 	for _, tt := range tests {