diff --git a/src/feature/create-album/utils/checkImages.test.ts b/src/feature/create-album/utils/checkImages.test.ts
new file mode 100644
index 0000000..ff51c0e
--- /dev/null
+++ b/src/feature/create-album/utils/checkImages.test.ts
@@ -0,0 +1,43 @@
+import { checkAvailableCount } from '@/feature/create-album/api/checkAvailableCount';
+import { validateImages } from '@/feature/create-album/utils/validateImages';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { checkImages } from './checkImages';
+
+// Mock dependencies
+vi.mock('@/feature/create-album/api/checkAvailableCount', () => ({
+  checkAvailableCount: vi.fn(),
+}));
+
+vi.mock('@/feature/create-album/utils/validateImages', () => ({
+  validateImages: vi.fn(),
+}));
+
+describe('checkImages', () => {
+  const mockFiles = [new File([], 'test1.jpg')];
+  const albumId = 'test-album-id';
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return oversized files and available count', async () => {
+    const mockOversizedFiles = ['oversized.jpg'];
+    const mockAvailableCount = 10;
+
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateImages as any).mockReturnValue({
+      oversizedFiles: mockOversizedFiles,
+    });
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (checkAvailableCount as any).mockResolvedValue(mockAvailableCount);
+
+    const result = await checkImages(mockFiles, albumId);
+
+    expect(result).toEqual({
+      oversizedFiles: mockOversizedFiles,
+      availableCount: mockAvailableCount,
+    });
+    expect(validateImages).toHaveBeenCalledWith(mockFiles);
+    expect(checkAvailableCount).toHaveBeenCalledWith(albumId);
+  });
+});
diff --git a/src/feature/create-album/utils/handleFileUpload.test.ts b/src/feature/create-album/utils/handleFileUpload.test.ts
new file mode 100644
index 0000000..ff5d1f0
--- /dev/null
+++ b/src/feature/create-album/utils/handleFileUpload.test.ts
@@ -0,0 +1,114 @@
+import { presignedAndUploadToNCP } from '@/global/api/presignedAndUploadToNCP';
+import { useUploadingStore } from '@/store/useUploadingStore';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { getFilesWithCaptureTime } from './getFilesWithCaptureTime';
+import { handleFileUpload } from './handleFileUpload';
+import { convertHeicFilesToJpeg } from './heicToJpeg';
+import { saveFilesToStore } from './saveFilesToStore';
+import { sortImagesByDate } from './sortImagesByDate';
+import { validateUpload } from './validateUpload';
+
+// Mock dependencies
+vi.mock('@/global/api/presignedAndUploadToNCP', () => ({
+  presignedAndUploadToNCP: vi.fn(),
+}));
+
+vi.mock('@/store/useUploadingStore', () => ({
+  useUploadingStore: {
+    getState: vi.fn().mockReturnValue({
+      setUploaded: vi.fn(),
+      setUploadedCount: vi.fn(),
+    }),
+  },
+}));
+
+vi.mock('./getFilesWithCaptureTime', () => ({
+  getFilesWithCaptureTime: vi.fn(),
+}));
+
+vi.mock('./heicToJpeg', () => ({
+  convertHeicFilesToJpeg: vi.fn(),
+}));
+
+vi.mock('./saveFilesToStore', () => ({
+  saveFilesToStore: vi.fn(),
+}));
+
+vi.mock('./sortImagesByDate', () => ({
+  sortImagesByDate: vi.fn(),
+}));
+
+vi.mock('./validateUpload', () => ({
+  validateUpload: vi.fn(),
+}));
+
+describe('handleFileUpload', () => {
+  const mockRouter = { push: vi.fn(), replace: vi.fn() };
+  const albumId = 'test-album-id';
+  const mockFile = new File(['content'], 'test.jpg', { type: 'image/jpeg' });
+  const mockEvent = {
+    target: {
+      files: [mockFile],
+      value: 'some-value',
+    },
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  } as any;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    // Default mock implementations
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (sortImagesByDate as any).mockResolvedValue([mockFile]);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (convertHeicFilesToJpeg as any).mockResolvedValue([mockFile]);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateUpload as any).mockResolvedValue({ ok: true });
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (getFilesWithCaptureTime as any).mockResolvedValue([
+      { file: mockFile, captureTime: '2023-01-01' },
+    ]);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (presignedAndUploadToNCP as any).mockResolvedValue({
+      success: 1,
+      failed: 0,
+    });
+  });
+
+  it('should orchestrate the upload flow correctly', async () => {
+    await handleFileUpload(mockEvent, albumId, mockRouter);
+
+    expect(sortImagesByDate).toHaveBeenCalled();
+    expect(convertHeicFilesToJpeg).toHaveBeenCalled();
+    expect(validateUpload).toHaveBeenCalled();
+    expect(useUploadingStore.getState().setUploaded).toHaveBeenCalledWith(true);
+    expect(mockRouter.push).toHaveBeenCalledWith(`/album/${albumId}/waiting`);
+    expect(getFilesWithCaptureTime).toHaveBeenCalled();
+    expect(presignedAndUploadToNCP).toHaveBeenCalled();
+    expect(useUploadingStore.getState().setUploadedCount).toHaveBeenCalledWith(
+      1,
+    );
+  });
+
+  it('should handle validation failure', async () => {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateUpload as any).mockResolvedValue({ ok: false, reason: 'size' });
+
+    await handleFileUpload(mockEvent, albumId, mockRouter);
+
+    expect(saveFilesToStore).toHaveBeenCalled();
+    expect(mockRouter.push).toHaveBeenCalledWith(`/album/${albumId}/waiting`);
+    expect(presignedAndUploadToNCP).not.toHaveBeenCalled();
+  });
+
+  it('should not redirect if stay option is true', async () => {
+    await handleFileUpload(mockEvent, albumId, mockRouter, { stay: true });
+
+    expect(mockRouter.push).not.toHaveBeenCalled();
+  });
+
+  it('should clear input value after execution', async () => {
+    await handleFileUpload(mockEvent, albumId, mockRouter);
+
+    expect(mockEvent.target.value).toBe('');
+  });
+});
diff --git a/src/feature/create-album/utils/heicToJpeg.test.ts b/src/feature/create-album/utils/heicToJpeg.test.ts
new file mode 100644
index 0000000..3ad1fa0
--- /dev/null
+++ b/src/feature/create-album/utils/heicToJpeg.test.ts
@@ -0,0 +1,75 @@
+import Toast from '@/global/components/toast/Toast';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { convertHeicFilesToJpeg } from './heicToJpeg';
+
+// Mock dependencies
+vi.mock('@/global/components/toast/Toast', () => ({
+  default: {
+    alert: vi.fn(),
+  },
+}));
+
+vi.mock('heic-to', () => ({
+  heicTo: vi.fn().mockImplementation(async ({ blob }) => {
+    // Return a dummy blob as if it were a JPEG
+    return new Blob(['dummy-jpeg-content'], { type: 'image/jpeg' });
+  }),
+}));
+
+describe('convertHeicFilesToJpeg', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return original files if no HEIC files are present', async () => {
+    const files = [
+      new File(['content'], 'test1.jpg', { type: 'image/jpeg' }),
+      new File(['content'], 'test2.png', { type: 'image/png' }),
+    ];
+
+    const result = await convertHeicFilesToJpeg(files);
+
+    expect(result).toHaveLength(2);
+    expect(result[0].name).toBe('test1.jpg');
+    expect(result[1].name).toBe('test2.png');
+    expect(Toast.alert).not.toHaveBeenCalled();
+  });
+
+  it('should convert HEIC files to JPEG', async () => {
+    const files = [
+      new File(['heic-content'], 'image.heic', { type: 'image/heic' }),
+      new File(['jpg-content'], 'image.jpg', { type: 'image/jpeg' }),
+    ];
+
+    const result = await convertHeicFilesToJpeg(files);
+
+    expect(result).toHaveLength(2);
+    // The first file should be converted to jpg
+    expect(result[0].name).toBe('image.jpg');
+    expect(result[0].type).toBe('image/jpeg');
+    // The second file should remain as is
+    expect(result[1].name).toBe('image.jpg');
+    expect(Toast.alert).toHaveBeenCalledWith(
+      '1개의 HEIC 파일을 변환 중입니다...',
+    );
+  });
+
+  it('should handle conversion failure gracefully', async () => {
+    const { heicTo } = await import('heic-to');
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (heicTo as any).mockRejectedValueOnce(new Error('Conversion failed'));
+
+    const files = [
+      new File(['heic-content'], 'fail.heic', { type: 'image/heic' }),
+    ];
+
+    const result = await convertHeicFilesToJpeg(files);
+
+    expect(result).toHaveLength(1);
+    // Should return original file on failure
+    expect(result[0].name).toBe('fail.heic');
+    expect(Toast.alert).toHaveBeenCalledWith(
+      'fail.heic 파일의 변환에 실패했습니다.',
+    );
+  });
+});
diff --git a/src/feature/create-album/utils/validateUpload.test.ts b/src/feature/create-album/utils/validateUpload.test.ts
new file mode 100644
index 0000000..b7fc956
--- /dev/null
+++ b/src/feature/create-album/utils/validateUpload.test.ts
@@ -0,0 +1,74 @@
+import { checkAvailableCount } from '@/feature/create-album/api/checkAvailableCount';
+import { validateImageCount } from '@/feature/create-album/utils/validateImages';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { validateUpload } from './validateUpload';
+
+// Mock dependencies
+vi.mock('@/feature/create-album/api/checkAvailableCount', () => ({
+  checkAvailableCount: vi.fn(),
+}));
+
+vi.mock('@/feature/create-album/utils/validateImages', () => ({
+  validateImageCount: vi.fn(),
+}));
+
+describe('validateUpload', () => {
+  const mockFiles = [new File([], 'test1.jpg'), new File([], 'test2.jpg')];
+  const albumId = 'test-album-id';
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return ok: true when validation passes', async () => {
+    // Mock validateImageCount to return 0 (no oversized files)
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateImageCount as any).mockReturnValue(0);
+    // Mock checkAvailableCount to return enough space
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (checkAvailableCount as any).mockResolvedValue(5);
+
+    const result = await validateUpload(mockFiles, albumId);
+
+    expect(result).toEqual({ ok: true });
+  });
+
+  it('should return ok: false with reason: size when files are oversized', async () => {
+    // Mock validateImageCount to return 1 (1 oversized file)
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateImageCount as any).mockReturnValue(1);
+    // Mock checkAvailableCount to return enough space
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (checkAvailableCount as any).mockResolvedValue(5);
+
+    const result = await validateUpload(mockFiles, albumId);
+
+    expect(result).toEqual({ ok: false, reason: 'size' });
+  });
+
+  it('should return ok: false with reason: count when file count exceeds limit', async () => {
+    // Mock validateImageCount to return 0
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateImageCount as any).mockReturnValue(0);
+    // Mock checkAvailableCount to return less than file count
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (checkAvailableCount as any).mockResolvedValue(1);
+
+    const result = await validateUpload(mockFiles, albumId);
+
+    expect(result).toEqual({ ok: false, reason: 'count' });
+  });
+
+  it('should return ok: false with reason: both when both checks fail', async () => {
+    // Mock validateImageCount to return 1
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (validateImageCount as any).mockReturnValue(1);
+    // Mock checkAvailableCount to return less than file count
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (checkAvailableCount as any).mockResolvedValue(1);
+
+    const result = await validateUpload(mockFiles, albumId);
+
+    expect(result).toEqual({ ok: false, reason: 'both' });
+  });
+});
diff --git a/src/feature/onboarding/hooks/useOnBoardingMutation.test.tsx b/src/feature/onboarding/hooks/useOnBoardingMutation.test.tsx
new file mode 100644
index 0000000..8ce1a8a
--- /dev/null
+++ b/src/feature/onboarding/hooks/useOnBoardingMutation.test.tsx
@@ -0,0 +1,67 @@
+import { api } from '@/global/utils/api';
+import { useMutation } from '@tanstack/react-query';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { useOnBoardingMutation } from './useOnBoardingMutation';
+
+// Mock api
+vi.mock('@/global/utils/api', () => ({
+  api: {
+    post: vi.fn(),
+  },
+}));
+
+// Mock useMutation
+vi.mock('@tanstack/react-query', () => ({
+  useMutation: vi.fn(),
+}));
+
+describe('useOnBoardingMutation', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should call useMutation with correct mutationFn', () => {
+    useOnBoardingMutation();
+
+    expect(useMutation).toHaveBeenCalledWith(
+      expect.objectContaining({
+        mutationFn: expect.any(Function),
+      }),
+    );
+  });
+
+  it('should call api.post when mutationFn is executed', async () => {
+    // Capture the mutationFn passed to useMutation
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    let capturedMutationFn: any;
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (useMutation as any).mockImplementation(({ mutationFn }: any) => {
+      capturedMutationFn = mutationFn;
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      return {} as any;
+    });
+
+    useOnBoardingMutation();
+
+    const mockPayload = {
+      name: 'Test User',
+      imageCode: 'img-123',
+      isServiceAgreement: true,
+      isUserInfoAgreement: true,
+      isMarketingAgreement: false,
+      isThirdPartyAgreement: true,
+    };
+
+    const mockResponse = { result: { success: true } };
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    (api.post as any).mockResolvedValue(mockResponse);
+
+    // Execute the captured mutationFn
+    await capturedMutationFn(mockPayload);
+
+    expect(api.post).toHaveBeenCalledWith({
+      path: expect.stringContaining('/user/onboarding'),
+      body: mockPayload,
+    });
+  });
+});
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..432b08c
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,13 @@
+import path from 'path';
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    environment: 'node', // Default to node, override per file if needed
+  },
+  resolve: {
+    alias: {
+      '@': path.resolve(__dirname, './src'),
+    },
+  },
+});