diff --git a/src/app/routes/PrivateRoute.tsx b/src/app/routes/PrivateRoute.tsx
index b9cac16..b47472e 100644
--- a/src/app/routes/PrivateRoute.tsx
+++ b/src/app/routes/PrivateRoute.tsx
@@ -9,8 +9,13 @@ const PrivateRoute = ({
   children: React.ReactNode;
 }): JSX.Element => {
   const user = useAuthStore((state) => state.user);
+  const isLoading = useAuthStore((state) => state.isLoading);
   const location = useLocation();
 
+  if (isLoading) {
+    return <div>Loading...</div>;
+  }
+
   if (!user) {
     return <Navigate to={`/login?redirect=${location.pathname}`} replace />;
   }
diff --git a/src/entities/user/api/userApi.ts b/src/entities/user/api/userApi.ts
deleted file mode 100644
index 0538fe0..0000000
--- a/src/entities/user/api/userApi.ts
+++ /dev/null
@@ -1,18 +0,0 @@
-import { doc, setDoc, getDoc } from "firebase/firestore";
-
-import { db } from "@shared/firebase/firebase";
-import type { User } from "@shared/types/user";
-
-export const saveUser = async (uid: string, userInfo: User): Promise<void> => {
-  const userDoc = doc(db, "users", uid);
-  await setDoc(userDoc, userInfo);
-};
-
-export const getUser = async (uid: string): Promise<User | null> => {
-  const userDoc = doc(db, "users", uid);
-  const userSnap = await getDoc(userDoc);
-  if (userSnap.exists()) {
-    return userSnap.data() as User;
-  }
-  return null;
-};
diff --git a/src/entities/user/hooks/useSignUp.ts b/src/entities/user/hooks/useSignUp.ts
index 533673e..b5bf429 100644
--- a/src/entities/user/hooks/useSignUp.ts
+++ b/src/entities/user/hooks/useSignUp.ts
@@ -1,7 +1,6 @@
 import { useNavigate } from "react-router-dom";
 
-import { saveUser } from "@entities/user/api/userApi";
-
+import { saveUser } from "@shared/api/userApi";
 import { useAuthStore } from "@shared/stores/authStore";
 import type { UserInput } from "@shared/types/user";
 
diff --git a/src/entities/user/hooks/useUpdateUser.ts b/src/entities/user/hooks/useUpdateUser.ts
new file mode 100644
index 0000000..6d6f397
--- /dev/null
+++ b/src/entities/user/hooks/useUpdateUser.ts
@@ -0,0 +1,29 @@
+import {
+  useMutation,
+  useQueryClient,
+  type UseMutationResult,
+} from "@tanstack/react-query";
+
+import { updateUser } from "@shared/api/userApi";
+import type { User } from "@shared/types/user";
+
+export const useUpdateUser = (): UseMutationResult<
+  void,
+  Error,
+  {
+    uid: string;
+    userInfo: Partial<User>;
+  },
+  unknown
+> => {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: ({ uid, userInfo }: { uid: string; userInfo: Partial<User> }) =>
+      updateUser(uid, userInfo),
+    onSuccess: (_, { uid }) => {
+      // 유저 프로필 쿼리 무효화하여 최신 데이터로 갱신
+      queryClient.invalidateQueries({ queryKey: ["userProfile", uid] });
+    },
+  });
+};
diff --git a/src/entities/user/hooks/useUpdateUserForm.ts b/src/entities/user/hooks/useUpdateUserForm.ts
new file mode 100644
index 0000000..fa7b6be
--- /dev/null
+++ b/src/entities/user/hooks/useUpdateUserForm.ts
@@ -0,0 +1,92 @@
+import { useState } from "react";
+
+import type { User, UserInput, UserRole } from "@shared/types/user";
+import { UserExperience } from "@shared/types/user";
+
+interface UseUpdateUserFormProps {
+  defaultUser: User;
+}
+
+interface UseUpdateUserFormReturn {
+  name: string;
+  userRole: string;
+  experience: string;
+  introduceMyself: string;
+  errors: {
+    name: boolean;
+    userRole: boolean;
+    experience: boolean;
+  };
+  handleChange: (
+    field: "name" | "userRole" | "experience" | "introduceMyself"
+  ) => (value: string) => void;
+  handleSubmit: () => UserInput | null;
+}
+
+export function useUpdateUserForm({
+  defaultUser,
+}: UseUpdateUserFormProps): UseUpdateUserFormReturn {
+  const [name, setName] = useState(defaultUser.name);
+  const [userRole, setUserRole] = useState<string>(defaultUser.userRole);
+  const [experience, setExperience] = useState<string>(defaultUser.experience);
+  const [introduceMyself, setIntroduceMyself] = useState(
+    defaultUser.introduceMyself || ""
+  );
+  const [errors, setErrors] = useState({
+    name: false,
+    userRole: false,
+    experience: false,
+  });
+
+  const handleChange =
+    (field: "name" | "userRole" | "experience" | "introduceMyself") =>
+    (value: string) => {
+      switch (field) {
+        case "name":
+          setName(value);
+          if (errors.name) setErrors((prev) => ({ ...prev, name: false }));
+          break;
+        case "userRole":
+          setUserRole(value);
+          if (errors.userRole)
+            setErrors((prev) => ({ ...prev, userRole: false }));
+          break;
+        case "experience":
+          setExperience(value);
+          if (errors.experience)
+            setErrors((prev) => ({ ...prev, experience: false }));
+          break;
+        case "introduceMyself":
+          setIntroduceMyself(value);
+          break;
+      }
+    };
+
+  const handleSubmit = (): UserInput | null => {
+    if (name === "" || userRole === "" || experience === "") {
+      setErrors({
+        name: name === "",
+        userRole: userRole === "",
+        experience: experience === "",
+      });
+      return null;
+    }
+
+    return {
+      name,
+      userRole: userRole as UserRole,
+      experience: experience as UserExperience,
+      introduceMyself: introduceMyself || "",
+    };
+  };
+
+  return {
+    name,
+    userRole,
+    experience,
+    introduceMyself,
+    errors,
+    handleChange,
+    handleSubmit,
+  };
+}
diff --git a/src/entities/user/ui/SubmitButton.tsx b/src/entities/user/ui/SubmitButton.tsx
index 83ad08e..84f88fd 100644
--- a/src/entities/user/ui/SubmitButton.tsx
+++ b/src/entities/user/ui/SubmitButton.tsx
@@ -1,8 +1,16 @@
 import { Button, styled } from "@mui/material";
 import type { JSX } from "react";
 
-const SubmitButton = ({ onClick }: { onClick: () => void }): JSX.Element => {
-  return <SignupButton onClick={onClick}>회원가입 완료</SignupButton>;
+interface SubmitButtonProps {
+  onClick: () => void;
+  text?: string;
+}
+
+const SubmitButton = ({
+  onClick,
+  text = "회원가입 완료",
+}: SubmitButtonProps): JSX.Element => {
+  return <SignupButton onClick={onClick}>{text}</SignupButton>;
 };
 
 export default SubmitButton;
diff --git a/src/entities/user/ui/UpdateUserForm.tsx b/src/entities/user/ui/UpdateUserForm.tsx
new file mode 100644
index 0000000..d8307c3
--- /dev/null
+++ b/src/entities/user/ui/UpdateUserForm.tsx
@@ -0,0 +1,253 @@
+import {
+  Box,
+  MenuItem,
+  Select,
+  TextField,
+  Typography,
+  FormControl,
+  FormHelperText,
+  InputLabel,
+  Dialog,
+  DialogTitle,
+  DialogContent,
+  DialogActions,
+  Button,
+} from "@mui/material";
+import { styled } from "@mui/material/styles";
+import { type JSX } from "react";
+import { useState } from "react";
+
+import { useUpdateUserForm } from "@entities/user/hooks/useUpdateUserForm";
+
+import type { User, UserInput } from "@shared/types/user";
+import { UserExperience } from "@shared/types/user";
+
+interface UpdateUserFormProps {
+  defaultUser: User;
+  onSubmit: (userInfo: UserInput) => void;
+  onCancel: () => void;
+}
+
+const UpdateUserForm = ({
+  defaultUser,
+  onSubmit,
+  onCancel,
+}: UpdateUserFormProps): JSX.Element => {
+  const {
+    name,
+    userRole,
+    experience,
+    introduceMyself,
+    errors,
+    handleChange,
+    handleSubmit,
+  } = useUpdateUserForm({ defaultUser });
+
+  const [showConfirmDialog, setShowConfirmDialog] = useState(false);
+
+  const handleFormSubmit = (): void => {
+    const result = handleSubmit();
+    if (result) {
+      setShowConfirmDialog(true);
+    }
+  };
+
+  const handleConfirmSubmit = (): void => {
+    const result = handleSubmit();
+    if (result) {
+      onSubmit(result);
+      setShowConfirmDialog(false);
+    }
+  };
+
+  const handleCancelConfirm = (): void => {
+    setShowConfirmDialog(false);
+  };
+
+  return (
+    <>
+      <FormContainer>
+        <Title variant="h5">프로필 수정</Title>
+        {/* 이름 입력 */}
+        <FormControl error={errors.name} variant="outlined" fullWidth>
+          <StyledTextField
+            label="🙋 닉네임 *"
+            variant="outlined"
+            value={name}
+            onChange={(e) => handleChange("name")(e.target.value)}
+            error={errors.name}
+            onFocus={() => errors.name && handleChange("name")(name)}
+            InputLabelProps={{ shrink: true }}
+          />
+          {errors.name && <ErrorText>이름을 입력해주세요.</ErrorText>}
+        </FormControl>
+        {/* 이메일 입력 (disabled) */}
+        <FormControl variant="outlined" fullWidth>
+          <StyledTextField
+            label="📧 이메일"
+            variant="outlined"
+            value={defaultUser.email}
+            disabled
+            InputLabelProps={{ shrink: true }}
+          />
+        </FormControl>
+        {/* 직무 선택 */}
+        <FormControl error={errors.userRole} variant="outlined" fullWidth>
+          <InputLabel shrink>👔 직무 *</InputLabel>
+          <StyledSelect
+            label="👔 직무 *"
+            value={userRole}
+            onChange={(e) => handleChange("userRole")(e.target.value as string)}
+            displayEmpty
+          >
+            <MenuItem value="">직무 선택</MenuItem>
+            <MenuItem value="frontend">프론트엔드</MenuItem>
+            <MenuItem value="backend">백엔드</MenuItem>
+            <MenuItem value="fullstack">풀스택</MenuItem>
+            <MenuItem value="designer">디자이너</MenuItem>
+            <MenuItem value="pm">PM</MenuItem>
+          </StyledSelect>
+          {errors.userRole && <ErrorText>직무를 선택해주세요.</ErrorText>}
+        </FormControl>
+        {/* 경력 선택 */}
+        <FormControl error={errors.experience} variant="outlined" fullWidth>
+          <InputLabel shrink>💼 경력 *</InputLabel>
+          <StyledSelect
+            label="💼 경력 *"
+            value={experience}
+            onChange={(e) =>
+              handleChange("experience")(e.target.value as string)
+            }
+            displayEmpty
+          >
+            <MenuItem value="">경력 선택</MenuItem>
+            <MenuItem value={UserExperience.junior}>주니어 (3년 이하)</MenuItem>
+            <MenuItem value={UserExperience.mid}>
+              미들 (3년 이상 10년 이하)
+            </MenuItem>
+            <MenuItem value={UserExperience.senior}>
+              시니어 (10년 이상)
+            </MenuItem>
+          </StyledSelect>
+          {errors.experience && <ErrorText>경력을 선택해주세요.</ErrorText>}
+        </FormControl>
+        <StyledTextField
+          label="💬 자기소개"
+          variant="outlined"
+          value={introduceMyself}
+          onChange={(e) => handleChange("introduceMyself")(e.target.value)}
+          placeholder="코딩하고 싶은 밤이에요~😘"
+          multiline
+          rows={4}
+          InputLabelProps={{ shrink: true }}
+        />
+        <ButtonContainer>
+          <CancelButton onClick={onCancel}>취소</CancelButton>
+          <SubmitButtonStyled onClick={handleFormSubmit}>
+            저장
+          </SubmitButtonStyled>
+        </ButtonContainer>
+      </FormContainer>
+
+      {/* 확인 다이얼로그 */}
+      <Dialog
+        open={showConfirmDialog}
+        onClose={handleCancelConfirm}
+        maxWidth="xs"
+      >
+        <DialogTitle sx={{ textAlign: "center", pb: 1 }}>
+          저장하시겠습니까?
+        </DialogTitle>
+        <DialogContent sx={{ textAlign: "center", pb: 2 }}>
+          <Typography variant="body2" color="text.secondary">
+            입력하신 정보로 프로필이 업데이트됩니다.
+          </Typography>
+        </DialogContent>
+        <DialogActions sx={{ justifyContent: "center", pb: 2, px: 3 }}>
+          <Button onClick={handleCancelConfirm} variant="outlined">
+            취소
+          </Button>
+          <Button
+            onClick={handleConfirmSubmit}
+            variant="contained"
+            color="primary"
+          >
+            확인
+          </Button>
+        </DialogActions>
+      </Dialog>
+    </>
+  );
+};
+
+export default UpdateUserForm;
+
+const FormContainer = styled(Box)({
+  display: "flex",
+  flexDirection: "column",
+  gap: "16px",
+  width: "100%",
+  maxWidth: "400px",
+  margin: "0 auto",
+  padding: "2rem 1rem",
+});
+
+const Title = styled(Typography)({
+  textAlign: "center",
+  marginBottom: "16px",
+});
+
+const StyledTextField = styled(TextField)({
+  width: "100%",
+});
+
+const StyledSelect = styled(Select)({
+  width: "100%",
+});
+
+const ErrorText = styled(FormHelperText)({
+  fontSize: "1.3rem",
+  color: "#f44336", // MUI 기본 error color
+  marginLeft: "14px",
+});
+
+const ButtonContainer = styled(Box)({
+  display: "flex",
+  marginTop: "8px",
+  gap: "2rem",
+  justifyContent: "space-between",
+});
+
+const CancelButton = styled("button")({
+  flex: 1,
+  padding: "12px 24px",
+  border: "1px solid #ccc",
+  borderRadius: "8px",
+  backgroundColor: "#fff",
+  color: "#666",
+  fontSize: "1.4rem",
+  fontWeight: 500,
+  cursor: "pointer",
+  transition: "all 0.2s ease",
+  "&:hover": {
+    backgroundColor: "#f5f5f5",
+    borderColor: "#999",
+  },
+});
+
+const SubmitButtonStyled = styled("button")({
+  flex: 1,
+  padding: "12px 24px",
+  border: "1px solid #1976d2",
+  borderRadius: "8px",
+  backgroundColor: "#1976d2",
+  color: "#fff",
+  fontSize: "1.4rem",
+  fontWeight: 500,
+  cursor: "pointer",
+  transition: "all 0.2s ease",
+  "&:hover": {
+    backgroundColor: "#1565c0",
+    borderColor: "#1565c0",
+  },
+});
diff --git a/src/entities/user/ui/user-profile/UserProfileCard.tsx b/src/entities/user/ui/user-profile/UserProfileCard.tsx
index a366c09..cdda2b0 100644
--- a/src/entities/user/ui/user-profile/UserProfileCard.tsx
+++ b/src/entities/user/ui/user-profile/UserProfileCard.tsx
@@ -7,12 +7,21 @@ import {
   CardContent,
   IconButton,
   Divider,
+  Dialog,
+  DialogContent,
+  Tooltip,
 } from "@mui/material";
 import { styled as muiStyled } from "@mui/material/styles";
 import type { ComponentType, JSX } from "react";
+import { useState } from "react";
+
+import { useUpdateUser } from "@entities/user/hooks/useUpdateUser";
+import UpdateUserForm from "@entities/user/ui/UpdateUserForm";
 
 import { useProjectStore } from "@shared/stores/projectStore";
-import type { User } from "@shared/types/user";
+import type { User, UserInput } from "@shared/types/user";
+import { UserExperience } from "@shared/types/user";
+import SnackbarAlert from "@shared/ui/SnackbarAlert";
 
 import TabWithBadge from "./TapWithBadge";
 
@@ -33,10 +42,11 @@ const userRoleMap: Record<string, string> = {
   designer: "디자이너",
   pm: "PM",
 };
+
 const experienceMap: Record<string, string> = {
-  junior: "주니어 (3년 이하) 🌱",
-  mid: "미들 (3년 이상 10년 이하) 🌿",
-  senior: "시니어 (10년 이상) 🌳",
+  [UserExperience.junior]: "주니어 (3년 이하) 🌱",
+  [UserExperience.mid]: "미들 (3년 이상 10년 이하) 🌿",
+  [UserExperience.senior]: "시니어 (10년 이상) 🌳",
 };
 
 const UserProfileCard = ({
@@ -47,56 +57,146 @@ const UserProfileCard = ({
   ProfileTabChip,
 }: UserProfileCardProps): JSX.Element => {
   const { likeProjects, appliedProjects } = useProjectStore();
+  const [openModal, setOpenModal] = useState(false);
+  const [snackbarOpen, setSnackbarOpen] = useState(false);
+
+  const updateUserMutation = useUpdateUser();
+
+  const handleOpenModal = (): void => {
+    setOpenModal(true);
+  };
+
+  const handleCloseModal = (): void => {
+    setOpenModal(false);
+  };
+
+  const handleSubmitUpdate = async (userInfo: UserInput): Promise<void> => {
+    try {
+      await updateUserMutation.mutateAsync({
+        uid: userProfile.id,
+        userInfo,
+      });
+
+      setOpenModal(false);
+      setSnackbarOpen(true);
+    } catch (error) {
+      console.error("프로필 업데이트 실패:", error);
+      // 에러 처리 로직 추가 가능
+    }
+  };
 
   return (
-    <ProfileCard>
-      <ProfileCardContent>
-        <ProfileCardHeader>
-          <IconButton size="large" aria-label="프로필 수정">
-            <SettingsIcon sx={{ fontSize: "2rem" }} />
-          </IconButton>
-        </ProfileCardHeader>
-        <ProfileMainRow>
-          <ProfileAvatar src={userProfile.avatar} />
-          <ProfileInfoCol>
+    <>
+      <ProfileCard>
+        <ProfileCardContent>
+          <ProfileCardHeader>
+            <Tooltip
+              title="내 정보 수정하기"
+              arrow
+              placement="left"
+              componentsProps={{
+                tooltip: {
+                  sx: {
+                    fontSize: "1.4rem",
+                    padding: "8px 12px",
+                    backgroundColor: "rgba(0, 0, 0, 0.47)",
+                    color: "#fff",
+                    borderRadius: "6px",
+                    fontWeight: 500,
+                  },
+                },
+                arrow: {
+                  sx: {
+                    color: "rgba(0, 0, 0, 0.47)",
+                  },
+                },
+              }}
+            >
+              <IconButton
+                size="large"
+                aria-label="프로필 수정"
+                onClick={handleOpenModal}
+              >
+                <SettingsIcon sx={{ fontSize: "2rem" }} />
+              </IconButton>
+            </Tooltip>
+          </ProfileCardHeader>
+          <ProfileMainRow>
+            <ProfileAvatar src={userProfile.avatar} />
+            <ProfileInfoCol>
+              <Typography
+                variant="h2"
+                fontWeight={700}
+                sx={{ paddingBottom: "1.5rem" }}
+              >
+                {userProfile.name}
+              </Typography>
+              <Typography variant="body1">
+                {userRoleMap[userProfile.userRole] || userProfile.userRole}
+              </Typography>
+              <Typography variant="body2">
+                {experienceMap[userProfile.experience] ||
+                  userProfile.experience}
+              </Typography>
+            </ProfileInfoCol>
+          </ProfileMainRow>
+          <Box mt={2} width="100%" padding="0 1rem">
             <Typography
-              variant="h2"
-              fontWeight={700}
-              sx={{ paddingBottom: "1.5rem" }}
+              sx={{ whiteSpace: "pre-line", wordBreak: "break-word" }}
             >
-              {userProfile.name}
-            </Typography>
-            <Typography variant="body1">
-              {userRoleMap[userProfile.userRole] || userProfile.userRole}
+              {userProfile.introduceMyself}
             </Typography>
-            <Typography variant="body2">
-              {experienceMap[userProfile.experience] || userProfile.experience}
-            </Typography>
-          </ProfileInfoCol>
-        </ProfileMainRow>
-        <Box mt={2} width="100%" padding="0 1rem">
-          <Typography>{userProfile.introduceMyself}</Typography>
-        </Box>
-        <Divider sx={{ my: 2 }} />
-        <TabBadgeContainer>
-          {PROFILE_TABS.map((tabInfo, idx) => (
-            <TabWithBadge
-              key={tabInfo.label}
-              label={tabInfo.label}
-              count={
-                idx === 0
-                  ? likeProjects?.length || 0
-                  : appliedProjects?.length || 0
-              }
-              active={tab === idx}
-              onClick={() => setTab(idx)}
-              ProfileTabChip={ProfileTabChip}
-            />
-          ))}
-        </TabBadgeContainer>
-        <ProfileEmail>💌 • {userProfile.email}</ProfileEmail>
-      </ProfileCardContent>
-    </ProfileCard>
+          </Box>
+          <Divider sx={{ my: 2 }} />
+          <TabBadgeContainer>
+            {PROFILE_TABS.map((tabInfo, idx) => (
+              <TabWithBadge
+                key={tabInfo.label}
+                label={tabInfo.label}
+                count={
+                  idx === 0
+                    ? likeProjects?.length || 0
+                    : appliedProjects?.length || 0
+                }
+                active={tab === idx}
+                onClick={() => setTab(idx)}
+                ProfileTabChip={ProfileTabChip}
+              />
+            ))}
+          </TabBadgeContainer>
+          <ProfileEmail>💌 • {userProfile.email}</ProfileEmail>
+        </ProfileCardContent>
+      </ProfileCard>
+
+      {/* 프로필 수정 모달 */}
+      <Dialog
+        open={openModal}
+        onClose={handleCloseModal}
+        maxWidth="md"
+        PaperProps={{
+          sx: {
+            borderRadius: 2,
+            margin: 2,
+          },
+        }}
+      >
+        <DialogContent sx={{ padding: "2rem", py: 3 }}>
+          <UpdateUserForm
+            defaultUser={userProfile}
+            onSubmit={handleSubmitUpdate}
+            onCancel={handleCloseModal}
+          />
+        </DialogContent>
+      </Dialog>
+
+      {/* 스낵바 알림 */}
+      <SnackbarAlert
+        open={snackbarOpen}
+        onClose={() => setSnackbarOpen(false)}
+        message="프로필 정보가 업데이트되었습니다! ✨"
+        severity="success"
+      />
+    </>
   );
 };
 
@@ -105,13 +205,11 @@ export default UserProfileCard;
 // 스타일 컴포넌트 재사용
 const ProfileCard = muiStyled(Card)(({ theme }) => ({
   minWidth: 280,
-  maxWidth: "100%",
+  maxWidth: 380,
   borderRadius: 12,
   boxShadow: theme.shadows[2],
   position: "relative",
   padding: "0 2rem",
-  maxHeight: "350px",
-  overflow: "auto",
 }));
 const ProfileCardContent = muiStyled(CardContent)(({ theme }) => ({
   padding: theme.spacing(3),
diff --git a/src/features/auth/hooks/useSocialLogin.ts b/src/features/auth/hooks/useSocialLogin.ts
index beb08f4..132227f 100644
--- a/src/features/auth/hooks/useSocialLogin.ts
+++ b/src/features/auth/hooks/useSocialLogin.ts
@@ -2,6 +2,7 @@ import {
   signInWithPopup,
   fetchSignInMethodsForEmail,
   getAdditionalUserInfo,
+  type AuthError,
 } from "firebase/auth";
 import type { AuthProvider } from "firebase/auth";
 import { useNavigate, useSearchParams } from "react-router-dom";
@@ -18,46 +19,92 @@ export const useSocialLogin = (): {
   const socialLogin = async (provider: AuthProvider): Promise<void> => {
     try {
       const result = await signInWithPopup(auth, provider);
-      const user = result.user;
-
-      console.log("소셜 로그인 성공: ", user);
 
       // Firebase 신규 유저 여부 확인
       const additionalInfo = getAdditionalUserInfo(result);
       const isNewUser = additionalInfo?.isNewUser;
 
       if (isNewUser) {
-        navigate("/signup");
+        navigate("/signup", { state: { fromSocial: true } });
       } else {
         navigate(redirect);
       }
-    } catch (error: any) {
-      console.error("소셜 로그인 실패: ", error);
-
-      if (error.code !== "auth/account-exists-with-different-credential")
-        return;
+    } catch (error: unknown) {
+      const authError = error as AuthError;
 
-      const email = error.customData?.email;
-      if (!email) {
-        alert("이메일 정보를 가져올 수 없습니다.");
+      // 계정 충돌 에러 처리
+      if (authError.code === "auth/account-exists-with-different-credential") {
+        await handleAccountConflict(authError);
         return;
       }
 
+      // 기타 에러 처리
+      handleGeneralError(authError);
+    }
+  };
+
+  const handleAccountConflict = async (error: AuthError): Promise<void> => {
+    const email = error.customData?.email;
+    if (!email) {
+      showErrorSnackbar("이메일 정보를 가져올 수 없습니다.");
+      return;
+    }
+
+    try {
       const methods = await fetchSignInMethodsForEmail(auth, email);
       if (methods.length === 0) {
-        alert("이미 다른 로그인 방법으로 가입된 이메일입니다.");
+        showErrorSnackbar("이미 다른 로그인 방법으로 가입된 이메일입니다.");
         return;
       }
 
       if (methods.includes("google.com")) {
-        alert(
+        showErrorSnackbar(
           "이미 Google 계정으로 가입된 이메일입니다. Google 로그인을 이용해주세요."
         );
       } else {
-        alert(`이미 가입된 로그인 방법: ${methods.join(", ")}`);
+        showErrorSnackbar(`이미 가입된 로그인 방법: ${methods.join(", ")}`);
       }
+    } catch {
+      showErrorSnackbar("로그인 방법 조회 중 오류가 발생했습니다.");
     }
   };
 
+  const handleGeneralError = (error: AuthError): void => {
+    // 일반적인 에러 코드별 처리
+    switch (error.code) {
+      case "auth/popup-closed-by-user":
+        // 사용자가 팝업을 닫은 경우는 알림하지 않음
+        break;
+      case "auth/popup-blocked":
+        showErrorSnackbar("팝업이 차단되었습니다. 팝업 차단을 해제해주세요.");
+        break;
+      case "auth/network-request-failed":
+        showErrorSnackbar("네트워크 연결을 확인해주세요.");
+        break;
+      case "auth/user-disabled":
+        showErrorSnackbar("비활성화된 계정입니다.");
+        break;
+      case "auth/invalid-credential":
+        showErrorSnackbar("잘못된 로그인 정보입니다.");
+        break;
+      case "auth/operation-not-allowed":
+        showErrorSnackbar("해당 로그인 방법이 허용되지 않습니다.");
+        break;
+      case "auth/too-many-requests":
+        showErrorSnackbar(
+          "너무 많은 로그인 시도가 있었습니다. 잠시 후 다시 시도해주세요."
+        );
+        break;
+      default:
+        showErrorSnackbar("로그인 중 오류가 발생했습니다. 다시 시도해주세요.");
+    }
+  };
+
+  const showErrorSnackbar = (message: string): void => {
+    // TODO: 전역 스낵바 상태 관리로 에러 메시지 표시
+    // 예: useSnackbarStore.getState().showError(message);
+    console.error("로그인 에러:", message);
+  };
+
   return { socialLogin };
 };
diff --git a/src/features/auth/hooks/useUserProfile.ts b/src/features/auth/hooks/useUserProfile.ts
deleted file mode 100644
index 3038f9e..0000000
--- a/src/features/auth/hooks/useUserProfile.ts
+++ /dev/null
@@ -1,13 +0,0 @@
-import { useQuery, type UseQueryResult } from "@tanstack/react-query";
-
-import { getUser } from "@entities/user/api/userApi";
-
-import type { User } from "@shared/types/user";
-
-export function useUserProfile(uid: string): UseQueryResult<User | null> {
-  return useQuery<User | null>({
-    queryKey: ["userProfile", uid],
-    queryFn: () => getUser(uid),
-    enabled: !!uid, // uid가 있을 때만 쿼리 실행
-  });
-}
diff --git a/src/features/projects/hook/useProjectInsertForm.ts b/src/features/projects/hook/useProjectInsertForm.ts
index 2c7a37f..2b4b7c3 100644
--- a/src/features/projects/hook/useProjectInsertForm.ts
+++ b/src/features/projects/hook/useProjectInsertForm.ts
@@ -123,6 +123,7 @@ const initForm4 = {
 
 // 테스트용 form 입니다.
 const TestData = (user: User): ProjectItemInsertReq => ({
+  projectOwnerID: user.id, // 요거 추가!!
   projectOwner: {
     id: user.id,
     name: user.name,
diff --git a/src/pages/home/ui/HomePage.tsx b/src/pages/home/ui/HomePage.tsx
index 81afb70..a07c3c3 100644
--- a/src/pages/home/ui/HomePage.tsx
+++ b/src/pages/home/ui/HomePage.tsx
@@ -8,7 +8,6 @@ import ProjectCard from "@entities/projects/ui/projects-card/ProjectCard";
 import ProjectsStats from "@entities/projects/ui/projects-stats/ProjectsStats";
 
 const HomePage = (): JSX.Element => {
-  console.log("API_KEY: ", import.meta.env.VITE_API_KEY);
   const { data: projects } = useGetProjects({ pageSize: 3 });
 
   return (
diff --git a/src/pages/login/ui/LoginPage.tsx b/src/pages/login/ui/LoginPage.tsx
index 8461f08..8908cf6 100644
--- a/src/pages/login/ui/LoginPage.tsx
+++ b/src/pages/login/ui/LoginPage.tsx
@@ -6,7 +6,6 @@ import BackToHome from "@widgets/BackToHome/BackToHome";
 import { LoginForm } from "@features/auth/ui/LoginForm";
 
 const LoginPage = (): JSX.Element => {
-  console.log("API_KEY: ", import.meta.env.VITE_API_KEY);
   return (
     <PageWrapper>
       <Typography variant="h3" fontWeight={700} mb={1} color="#4F46E5B">
diff --git a/src/pages/signup/ui/SignUpPage.tsx b/src/pages/signup/ui/SignUpPage.tsx
index f79e6e9..f61b916 100644
--- a/src/pages/signup/ui/SignUpPage.tsx
+++ b/src/pages/signup/ui/SignUpPage.tsx
@@ -1,11 +1,33 @@
 import { Box, Paper, styled, Typography } from "@mui/material";
 import type { JSX } from "react";
+import { useState } from "react";
+import { useLocation, Navigate } from "react-router-dom";
 
 import BackToHome from "@widgets/BackToHome/BackToHome";
 
 import UserInfoForm from "@entities/user/ui/UserInfoForm";
 
+import SnackbarAlert from "@shared/ui/SnackbarAlert";
+
 const SignUpPage = (): JSX.Element => {
+  const location = useLocation();
+  const fromSocial = location.state?.fromSocial;
+  const [open, setOpen] = useState(!fromSocial);
+
+  if (!fromSocial) {
+    if (open) {
+      return (
+        <SnackbarAlert
+          open={open}
+          onClose={() => setOpen(false)}
+          message="잘못된 접근입니다."
+          severity="error"
+        />
+      );
+    }
+    return <Navigate to="/" replace />;
+  }
+
   return (
     <PageContainer>
       <Typography variant="h4" mb={2}>
diff --git a/src/pages/user-profile/ui/UserProfilePage.tsx b/src/pages/user-profile/ui/UserProfilePage.tsx
index 99e2b46..cd5fcb9 100644
--- a/src/pages/user-profile/ui/UserProfilePage.tsx
+++ b/src/pages/user-profile/ui/UserProfilePage.tsx
@@ -3,7 +3,6 @@ import { styled as muiStyled } from "@mui/material/styles";
 import type { JSX } from "react";
 import { useState, useEffect } from "react";
 
-import { useUserProfile } from "@features/auth/hooks/useUserProfile";
 import { removeProjectsFromUser } from "@features/projects/api/projectsApi";
 
 import { useProjectsByIds } from "@entities/projects/hook/useProjectsByIds";
@@ -11,6 +10,7 @@ import UserProfileCard from "@entities/user/ui/user-profile/UserProfileCard";
 import UserProfileHeader from "@entities/user/ui/user-profile/UserProfileHeader";
 import UserProfileProjectList from "@entities/user/ui/user-profile/UserProfileProjectList";
 
+import { useUserProfile } from "@shared/queries/useUserProfile";
 import { useAuthStore } from "@shared/stores/authStore";
 import { useProjectStore } from "@shared/stores/projectStore";
 import LoadingSpinner from "@shared/ui/loading-spinner/LoadingSpinner";
@@ -71,6 +71,7 @@ const UserProfilePage = (): JSX.Element => {
         gap={4}
         flexDirection={{ xs: "column", sm: "row" }}
         position="relative"
+        alignItems="flex-start"
       >
         {/* 왼쪽 프로필 사이드바 */}
         <UserProfileCard
diff --git a/src/shared/api/userApi.ts b/src/shared/api/userApi.ts
index 0538fe0..e2ce62d 100644
--- a/src/shared/api/userApi.ts
+++ b/src/shared/api/userApi.ts
@@ -1,4 +1,4 @@
-import { doc, setDoc, getDoc } from "firebase/firestore";
+import { doc, setDoc, getDoc, updateDoc } from "firebase/firestore";
 
 import { db } from "@shared/firebase/firebase";
 import type { User } from "@shared/types/user";
@@ -16,3 +16,11 @@ export const getUser = async (uid: string): Promise<User | null> => {
   }
   return null;
 };
+
+export const updateUser = async (
+  uid: string,
+  userInfo: Partial<User>
+): Promise<void> => {
+  const userDoc = doc(db, "users", uid);
+  await updateDoc(userDoc, userInfo);
+};
diff --git a/src/shared/types/project.ts b/src/shared/types/project.ts
index 46f3531..fc600f5 100644
--- a/src/shared/types/project.ts
+++ b/src/shared/types/project.ts
@@ -4,6 +4,7 @@ import type { ExpectedPeriod, ProjectSchedule } from "@shared/types/schedule";
 import type { User, UserRole } from "@shared/types/user";
 
 export interface ProjectItemInsertReq {
+  projectOwnerID: string; // 작성자
   projectOwner: User; // 프로젝트 오너 유저 정보
   status: RecruitmentStatus;
   category: ProjectCategory; // 프로젝트 분야