diff --git a/code/addons/vitest/src/vitest-plugin/index.test.ts b/code/addons/vitest/src/vitest-plugin/index.test.ts
new file mode 100644
index 000000000000..82bd93fad0ae
--- /dev/null
+++ b/code/addons/vitest/src/vitest-plugin/index.test.ts
@@ -0,0 +1,115 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const vitestTransform = vi.hoisted(() => vi.fn(() => ({ code: 'transformed code' })));
+const presetsApply = vi.hoisted(() => vi.fn());
+const withoutVitePlugins = vi.hoisted(() => vi.fn(async (plugins) => plugins));
+
+vi.mock('storybook/internal/common', () => ({
+  DEFAULT_FILES_PATTERN: '**/*.stories.@(js|jsx|mjs|ts|tsx)',
+  getInterpretedFile: vi.fn(() => undefined),
+  normalizeStories: vi.fn((stories) => stories),
+  optionalEnvToBoolean: vi.fn((value) => value === 'true'),
+  resolvePathInStorybookCache: vi.fn((...parts) => parts.join('/')),
+  validateConfigurationFiles: vi.fn(async () => {}),
+}));
+
+vi.mock('storybook/internal/core-server', () => ({
+  StoryIndexGenerator: {
+    findMatchingFilesForSpecifiers: vi.fn(async () => []),
+    storyFileNames: vi.fn(() => []),
+  },
+  Tag: { TEST: 'test' },
+  experimental_loadStorybook: vi.fn(async () => ({ presets: { apply: presetsApply } })),
+  mapStaticDir: vi.fn(),
+}));
+
+vi.mock('storybook/internal/csf-tools', () => ({
+  componentTransform: vi.fn(),
+  readConfig: vi.fn(),
+  vitestTransform,
+}));
+
+vi.mock('storybook/internal/server-errors', () => ({
+  MainFileMissingError: class MainFileMissingError extends Error {},
+}));
+
+vi.mock('storybook/internal/telemetry', () => ({
+  detectAgent: vi.fn(),
+  isTelemetryModuleEnabled: vi.fn(() => false),
+  isWithinInitialSession: vi.fn(),
+  oneWayHash: vi.fn(() => 'project-id'),
+  setTelemetryEnabled: vi.fn(async () => {}),
+  telemetry: vi.fn(),
+}));
+
+vi.mock('../../../../builders/builder-vite/src/utils/without-vite-plugins.ts', () => ({
+  withoutVitePlugins,
+}));
+
+vi.mock('./utils.ts', () => ({
+  requiresProjectAnnotations: vi.fn(async () => false),
+}));
+
+describe('storybookTest transform matching', () => {
+  const projectRoot = '/workspace/tést';
+
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+    vi.stubEnv('VITEST', 'true');
+    vi.stubEnv('VITEST_STORYBOOK', 'false');
+
+    presetsApply.mockImplementation(async (field, defaultValue) => {
+      switch (field) {
+        case 'stories':
+          return ['../src/**/*.stories.svelte'];
+        case 'viteCorePlugins':
+          return [];
+        case 'framework':
+          return { name: '@storybook/svelte-vite' };
+        case 'viteFinal':
+          return { plugins: [], root: projectRoot };
+        case 'staticDirs':
+          return [];
+        case 'core':
+          return {};
+        case 'features':
+          return {};
+        default:
+          return defaultValue;
+      }
+    });
+  });
+
+  it('transforms URL-encoded story ids when the project path contains non-ASCII characters', async () => {
+    const { storybookTest } = await import('./index.ts');
+    const plugins = await storybookTest({ configDir: `${projectRoot}/.storybook` });
+    const plugin = plugins.find((candidate) => candidate.name === 'vite-plugin-storybook-test');
+
+    expect(plugin).toBeDefined();
+
+    const configure = plugin!.config as unknown as (
+      config: { root: string; test: Record<string, never> },
+      env: { mode: string }
+    ) => unknown | Promise<unknown>;
+    const transform = plugin!.transform as unknown as (
+      code: string,
+      id: string
+    ) => unknown | Promise<unknown>;
+
+    await configure({ root: projectRoot, test: {} }, { mode: 'test' });
+    const result = await transform(
+      'export default {};',
+      '/workspace/t%C3%A9st/src/stories/Button.stories.svelte'
+    );
+
+    expect(vitestTransform).toHaveBeenCalledWith(
+      expect.objectContaining({
+        code: 'export default {};',
+        fileName: '/workspace/tést/src/stories/Button.stories.svelte',
+        configDir: `${projectRoot}/.storybook`,
+      })
+    );
+    expect(result).toEqual({ code: 'transformed code' });
+  });
+});
diff --git a/code/addons/vitest/src/vitest-plugin/index.ts b/code/addons/vitest/src/vitest-plugin/index.ts
index fce687c60e50..fec55d90eb7e 100644
--- a/code/addons/vitest/src/vitest-plugin/index.ts
+++ b/code/addons/vitest/src/vitest-plugin/index.ts
@@ -124,6 +124,14 @@ const getComponentTestPaths = (): string[] => {
   return envPaths.split(';').filter(Boolean);
 };
 
+const decodePathForMatching = (id: string) => {
+  try {
+    return decodeURI(id);
+  } catch {
+    return id;
+  }
+};
+
 const createComponentTestTransformPlugin = (presets: Presets, configDir: string): Plugin => {
   const storybookComponentTestPaths: string[] = getComponentTestPaths();
 
@@ -136,7 +144,8 @@ const createComponentTestTransformPlugin = (presets: Presets, configDir: string)
           return code;
         }
 
-        const resolvedId = path.resolve(id);
+        const idForMatching = decodePathForMatching(id);
+        const resolvedId = path.resolve(idForMatching);
         const matches = storybookComponentTestPaths.some(
           (testPath) =>
             resolvedId === testPath ||
@@ -151,7 +160,7 @@ const createComponentTestTransformPlugin = (presets: Presets, configDir: string)
 
         const result = await componentTransform({
           code,
-          fileName: id,
+          fileName: idForMatching,
           getComponentArgTypes: async ({ componentName, fileName }) =>
             presets.apply('internal_getArgTypesData', null, {
               componentFilePath: fileName,
@@ -502,12 +511,13 @@ export const storybookTest = async (options?: UserOptions): Promise<Plugin[]> =>
       }
     },
     async transform(code, id) {
-      const relativeId = relative(finalOptions.vitestRoot, id);
+      const idForMatching = decodePathForMatching(id);
+      const relativeId = relative(finalOptions.vitestRoot, idForMatching);
 
       if (match([relativeId], finalOptions.includeStories).length > 0) {
         return vitestTransform({
           code,
-          fileName: id,
+          fileName: idForMatching,
           configDir: finalOptions.configDir,
           tagsFilter: finalOptions.tags,
           stories: storiesGlobs,