diff --git a/packages/core/src/skills/skillManager.test.ts b/packages/core/src/skills/skillManager.test.ts
index 293115267c..ca3652a489 100644
--- a/packages/core/src/skills/skillManager.test.ts
+++ b/packages/core/src/skills/skillManager.test.ts
@@ -11,6 +11,15 @@ import * as path from 'node:path';
 import { SkillManager } from './skillManager.js';
 import { Storage } from '../config/storage.js';
 import { type GeminiCLIExtension } from '../config/config.js';
+import { loadSkillsFromDir, type SkillDefinition } from './skillLoader.js';
+
+vi.mock('./skillLoader.js', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('./skillLoader.js')>();
+  return {
+    ...actual,
+    loadSkillsFromDir: vi.fn(actual.loadSkillsFromDir),
+  };
+});
 
 describe('SkillManager', () => {
   let testRootDir: string;
@@ -71,6 +80,8 @@ description: project-desc
     vi.spyOn(storage, 'getProjectSkillsDir').mockReturnValue(projectDir);
 
     const service = new SkillManager();
+    // @ts-expect-error accessing private method for testing
+    vi.spyOn(service, 'discoverBuiltinSkills').mockResolvedValue(undefined);
     await service.discoverSkills(storage, [mockExtension]);
 
     const skills = service.getSkills();
@@ -126,6 +137,8 @@ description: project-desc
     vi.spyOn(storage, 'getProjectSkillsDir').mockReturnValue(projectDir);
 
     const service = new SkillManager();
+    // @ts-expect-error accessing private method for testing
+    vi.spyOn(service, 'discoverBuiltinSkills').mockResolvedValue(undefined);
     await service.discoverSkills(storage, [mockExtension]);
 
     const skills = service.getSkills();
@@ -138,6 +151,34 @@ description: project-desc
     expect(service.getSkills()[0].description).toBe('user-desc');
   });
 
+  it('should discover built-in skills', async () => {
+    const service = new SkillManager();
+    const mockBuiltinSkill: SkillDefinition = {
+      name: 'builtin-skill',
+      description: 'builtin-desc',
+      location: 'builtin-loc',
+      body: 'builtin-body',
+    };
+
+    vi.mocked(loadSkillsFromDir).mockImplementation(async (dir) => {
+      if (dir.endsWith('builtin')) {
+        return [{ ...mockBuiltinSkill }];
+      }
+      return [];
+    });
+
+    const storage = new Storage('/dummy');
+    vi.spyOn(storage, 'getProjectSkillsDir').mockReturnValue('/non-existent');
+    vi.spyOn(Storage, 'getUserSkillsDir').mockReturnValue('/non-existent');
+
+    await service.discoverSkills(storage);
+
+    const skills = service.getSkills();
+    expect(skills).toHaveLength(1);
+    expect(skills[0].name).toBe('builtin-skill');
+    expect(skills[0].isBuiltin).toBe(true);
+  });
+
   it('should filter disabled skills in getSkills but not in getAllSkills', async () => {
     const skillDir = path.join(testRootDir, 'skill1');
     await fs.mkdir(skillDir, { recursive: true });
@@ -156,6 +197,8 @@ description: desc1
     vi.spyOn(Storage, 'getUserSkillsDir').mockReturnValue('/non-existent');
 
     const service = new SkillManager();
+    // @ts-expect-error accessing private method for testing
+    vi.spyOn(service, 'discoverBuiltinSkills').mockResolvedValue(undefined);
     await service.discoverSkills(storage);
     service.setDisabledSkills(['skill1']);
 
diff --git a/packages/core/src/skills/skillManager.ts b/packages/core/src/skills/skillManager.ts
index 0279df5a65..6d301bd2f4 100644
--- a/packages/core/src/skills/skillManager.ts
+++ b/packages/core/src/skills/skillManager.ts
@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+import * as path from 'node:path';
+import { fileURLToPath } from 'node:url';
 import { Storage } from '../config/storage.js';
 import { type SkillDefinition, loadSkillsFromDir } from './skillLoader.js';
 import type { GeminiCLIExtension } from '../config/config.js';
@@ -56,9 +58,16 @@ export class SkillManager {
    * Discovers built-in skills.
    */
   private async discoverBuiltinSkills(): Promise<void> {
-    // Built-in skills can be added here.
-    // For now, this is a placeholder for where built-in skills will be loaded from.
-    // They could be loaded from a specific directory within the package.
+    const __dirname = path.dirname(fileURLToPath(import.meta.url));
+    const builtinDir = path.join(__dirname, 'builtin');
+
+    const builtinSkills = await loadSkillsFromDir(builtinDir);
+
+    for (const skill of builtinSkills) {
+      skill.isBuiltin = true;
+    }
+
+    this.addSkillsWithPrecedence(builtinSkills);
   }
 
   private addSkillsWithPrecedence(newSkills: SkillDefinition[]): void {
diff --git a/scripts/copy_bundle_assets.js b/scripts/copy_bundle_assets.js
index afd2b35ea4..d7cc87e8be 100644
--- a/scripts/copy_bundle_assets.js
+++ b/scripts/copy_bundle_assets.js
@@ -62,4 +62,15 @@ if (existsSync(docsSrc)) {
   console.log('Copied docs to bundle/docs/');
 }
 
+// 4. Copy Built-in Skills (packages/core/src/skills/builtin)
+const builtinSkillsSrc = join(root, 'packages/core/src/skills/builtin');
+const builtinSkillsDest = join(bundleDir, 'builtin');
+if (existsSync(builtinSkillsSrc)) {
+  cpSync(builtinSkillsSrc, builtinSkillsDest, {
+    recursive: true,
+    dereference: true,
+  });
+  console.log('Copied built-in skills to bundle/builtin/');
+}
+
 console.log('Assets copied to bundle/');
diff --git a/scripts/copy_files.js b/scripts/copy_files.js
index 4e32e61e00..fc612fd144 100644
--- a/scripts/copy_files.js
+++ b/scripts/copy_files.js
@@ -74,4 +74,13 @@ if (packageName === 'cli') {
   }
 }
 
+// Copy built-in skills for the core package.
+if (packageName === 'core') {
+  const builtinSkillsSource = path.join(sourceDir, 'skills', 'builtin');
+  const builtinSkillsTarget = path.join(targetDir, 'skills', 'builtin');
+  if (fs.existsSync(builtinSkillsSource)) {
+    fs.cpSync(builtinSkillsSource, builtinSkillsTarget, { recursive: true });
+  }
+}
+
 console.log('Successfully copied files.');