diff --git a/docs/config/index.md b/docs/config/index.md
index 35dc7d16be18..94eff5739fe1 100644
--- a/docs/config/index.md
+++ b/docs/config/index.md
@@ -985,6 +985,15 @@ Since Vitest 0.31.0, you can check your coverage report in Vitest UI: check [Vit
 
 Generate coverage report even when tests fail.
 
+#### coverage.allowExternal
+
+- **Type:** `boolean`
+- **Default:** `false`
+- **Available for providers:** `'v8' | 'istanbul'`
+- **CLI:** `--coverage.allowExternal`, `--coverage.allowExternal=false`
+
+Collect coverage of files outside the [project `root`](https://vitest.dev/config/#root).
+
 #### coverage.skipFull
 
 - **Type:** `boolean`
diff --git a/packages/coverage-istanbul/src/provider.ts b/packages/coverage-istanbul/src/provider.ts
index 84af13763de9..89cc3752a9c2 100644
--- a/packages/coverage-istanbul/src/provider.ts
+++ b/packages/coverage-istanbul/src/provider.ts
@@ -23,6 +23,7 @@ interface TestExclude {
     exclude?: string | string[]
     extension?: string | string[]
     excludeNodeModules?: boolean
+    relativePath?: boolean
   }): {
     shouldInstrument(filePath: string): boolean
     glob(cwd: string): Promise<string[]>
@@ -79,6 +80,7 @@ export class IstanbulCoverageProvider extends BaseCoverageProvider implements Co
       exclude: [...defaultExclude, ...defaultInclude, ...this.options.exclude],
       excludeNodeModules: true,
       extension: this.options.extension,
+      relativePath: !this.options.allowExternal,
     })
   }
 
diff --git a/packages/coverage-v8/src/provider.ts b/packages/coverage-v8/src/provider.ts
index 7733007804e3..7b3c28fa3095 100644
--- a/packages/coverage-v8/src/provider.ts
+++ b/packages/coverage-v8/src/provider.ts
@@ -30,6 +30,7 @@ interface TestExclude {
     exclude?: string | string[]
     extension?: string | string[]
     excludeNodeModules?: boolean
+    relativePath?: boolean
   }): {
     shouldInstrument(filePath: string): boolean
     glob(cwd: string): Promise<string[]>
@@ -79,6 +80,7 @@ export class V8CoverageProvider extends BaseCoverageProvider implements Coverage
       exclude: [...defaultExclude, ...defaultInclude, ...this.options.exclude],
       excludeNodeModules: true,
       extension: this.options.extension,
+      relativePath: !this.options.allowExternal,
     })
   }
 
diff --git a/packages/vitest/src/defaults.ts b/packages/vitest/src/defaults.ts
index 518324bfe8e1..2d696fb216fc 100644
--- a/packages/vitest/src/defaults.ts
+++ b/packages/vitest/src/defaults.ts
@@ -39,6 +39,7 @@ export const coverageConfigDefaults: ResolvedCoverageOptions = {
   reportOnFailure: false,
   reporter: [['text', {}], ['html', {}], ['clover', {}], ['json', {}]],
   extension: ['.js', '.cjs', '.mjs', '.ts', '.mts', '.cts', '.tsx', '.jsx', '.vue', '.svelte'],
+  allowExternal: false,
 }
 
 export const fakeTimersDefaults = {
diff --git a/packages/vitest/src/node/config.ts b/packages/vitest/src/node/config.ts
index b5f04b9f4887..ae10f25d3858 100644
--- a/packages/vitest/src/node/config.ts
+++ b/packages/vitest/src/node/config.ts
@@ -279,7 +279,7 @@ export function resolveConfig(
         ?? resolve(resolved.root, file),
     ),
   )
-  resolved.coverage.exclude.push(...resolved.setupFiles.map(file => relative(resolved.root, file)))
+  resolved.coverage.exclude.push(...resolved.setupFiles.map(file => `${resolved.coverage.allowExternal ? '**/' : ''}${relative(resolved.root, file)}`))
 
   resolved.forceRerunTriggers = [
     ...resolved.forceRerunTriggers,
diff --git a/packages/vitest/src/types/coverage.ts b/packages/vitest/src/types/coverage.ts
index 11c14578b0c5..e5caf29cd2f9 100644
--- a/packages/vitest/src/types/coverage.ts
+++ b/packages/vitest/src/types/coverage.ts
@@ -78,6 +78,7 @@ type FieldsWithDefaultValues =
   | 'exclude'
   | 'extension'
   | 'reportOnFailure'
+  | 'allowExternal'
 
 export type ResolvedCoverageOptions<T extends Provider = Provider> =
   & CoverageOptions<T>
@@ -216,6 +217,13 @@ export interface BaseCoverageOptions {
    * @default false
    */
   reportOnFailure?: boolean
+
+  /**
+   * Collect coverage of files outside the project `root`.
+   *
+   * @default false
+   */
+  allowExternal?: boolean
 }
 
 export interface CoverageIstanbulOptions extends BaseCoverageOptions {
diff --git a/test/coverage-test/coverage-report-tests/allow-external.test.ts b/test/coverage-test/coverage-report-tests/allow-external.test.ts
new file mode 100644
index 000000000000..fecca62077c0
--- /dev/null
+++ b/test/coverage-test/coverage-report-tests/allow-external.test.ts
@@ -0,0 +1,20 @@
+import fs from 'node:fs'
+import { expect, test } from 'vitest'
+
+const allowExternal = import.meta.env.VITE_COVERAGE_ALLOW_EXTERNAL
+
+test.skipIf(!allowExternal)('{ allowExternal: true } includes files outside project root', async () => {
+  expect(fs.existsSync('./coverage/test-utils/fixtures/math.ts.html')).toBe(true)
+
+  // Files inside project root should always be included
+  expect(fs.existsSync('./coverage/coverage-test/src/utils.ts.html')).toBe(true)
+})
+
+test.skipIf(allowExternal)('{ allowExternal: false } excludes files outside project root', async () => {
+  expect(fs.existsSync('./coverage/test-utils/fixtures/math.ts.html')).toBe(false)
+  expect(fs.existsSync('./test-utils/fixtures/math.ts.html')).toBe(false)
+  expect(fs.existsSync('./fixtures/math.ts.html')).toBe(false)
+
+  // Files inside project root should always be included
+  expect(fs.existsSync('./coverage/utils.ts.html')).toBe(true)
+})
diff --git a/test/coverage-test/option-tests/allow-external.test.ts b/test/coverage-test/option-tests/allow-external.test.ts
new file mode 100644
index 000000000000..95299ebf5d6b
--- /dev/null
+++ b/test/coverage-test/option-tests/allow-external.test.ts
@@ -0,0 +1,12 @@
+import { expect, test } from 'vitest'
+
+import { multiply } from '../src/utils'
+import * as ExternalMath from '../../test-utils/fixtures/math'
+
+test('calling files outside project root', () => {
+  expect(ExternalMath.sum(2, 3)).toBe(5)
+})
+
+test('multiply - add some files to report', () => {
+  expect(multiply(2, 3)).toBe(6)
+})
diff --git a/test/coverage-test/package.json b/test/coverage-test/package.json
index a699b16448cb..16525ea6e1bb 100644
--- a/test/coverage-test/package.json
+++ b/test/coverage-test/package.json
@@ -2,11 +2,12 @@
   "name": "@vitest/test-coverage",
   "private": true,
   "scripts": {
-    "test": "pnpm test:v8 && pnpm test:istanbul && pnpm test:custom && pnpm test:browser && pnpm test:types",
+    "test": "pnpm test:v8 && pnpm test:istanbul && pnpm test:custom && pnpm test:browser && pnpm test:options && pnpm test:types",
     "test:v8": "node ./testing.mjs --provider v8",
     "test:custom": "node ./testing.mjs --provider custom",
     "test:istanbul": "node ./testing.mjs --provider istanbul",
     "test:browser": "node ./testing.mjs --browser --provider istanbul",
+    "test:options": "node ./testing-options.mjs",
     "test:types": "vitest typecheck --run --reporter verbose"
   },
   "devDependencies": {
diff --git a/test/coverage-test/test/configuration-options.test-d.ts b/test/coverage-test/test/configuration-options.test-d.ts
index f4b0731a84e3..a0f42c0d4c62 100644
--- a/test/coverage-test/test/configuration-options.test-d.ts
+++ b/test/coverage-test/test/configuration-options.test-d.ts
@@ -103,6 +103,7 @@ test('provider module', () => {
             reporter: [['html', {}], ['json', { file: 'string' }]],
             reportsDirectory: 'string',
             reportOnFailure: true,
+            allowExternal: true,
           }
         },
         clean(_: boolean) {},
diff --git a/test/coverage-test/testing-options.mjs b/test/coverage-test/testing-options.mjs
new file mode 100644
index 000000000000..f86568c0720e
--- /dev/null
+++ b/test/coverage-test/testing-options.mjs
@@ -0,0 +1,69 @@
+import { startVitest } from 'vitest/node'
+
+/** @type {Record<string, Partial<import('vitest/config').UserConfig['test']>>[]} */
+const testCases = [
+  {
+    testConfig: {
+      name: 'allowExternal: true',
+      include: ['option-tests/allow-external.test.ts'],
+      coverage: {
+        allowExternal: true,
+        include: ['**/src/**', '**/test-utils/fixtures/**'],
+        reporter: 'html',
+      },
+    },
+    assertionConfig: {
+      include: ['coverage-report-tests/allow-external.test.ts'],
+      env: { VITE_COVERAGE_ALLOW_EXTERNAL: true },
+    },
+  },
+  {
+    testConfig: {
+      name: 'allowExternal: false',
+      include: ['option-tests/allow-external.test.ts'],
+      coverage: {
+        allowExternal: false,
+        include: ['**/src/**', '**/test-utils/fixtures/**'],
+        reporter: 'html',
+      },
+    },
+    assertionConfig: {
+      include: ['coverage-report-tests/allow-external.test.ts'],
+    },
+  },
+]
+
+for (const provider of ['v8', 'istanbul']) {
+  for (const { testConfig, assertionConfig } of testCases) {
+    // Run test case
+    await startVitest('test', ['option-tests/'], {
+      config: false,
+      watch: false,
+      ...testConfig,
+      name: `${provider} - ${testConfig.name}`,
+      coverage: {
+        enabled: true,
+        clean: true,
+        provider,
+        ...testConfig.coverage,
+      },
+    })
+
+    checkExit()
+
+    // Check generated coverage report
+    await startVitest('test', ['coverage-report-tests'], {
+      config: false,
+      watch: false,
+      ...assertionConfig,
+      name: `${provider} - assert ${testConfig.name}`,
+    })
+
+    checkExit()
+  }
+}
+
+function checkExit() {
+  if (process.exitCode)
+    process.exit(process.exitCode)
+}
diff --git a/test/test-utils/fixtures/math.ts b/test/test-utils/fixtures/math.ts
new file mode 100644
index 000000000000..0859841e5814
--- /dev/null
+++ b/test/test-utils/fixtures/math.ts
@@ -0,0 +1,7 @@
+export function sum(a: number, b: number) {
+  return a + b
+}
+
+export function multiply(a: number, b: number) {
+  return a * b
+}