diff --git a/packages/plugin-dts/src/utils.ts b/packages/plugin-dts/src/utils.ts
index 2a90cd524..e01e7c5fa 100644
--- a/packages/plugin-dts/src/utils.ts
+++ b/packages/plugin-dts/src/utils.ts
@@ -74,6 +74,15 @@ export async function pathExists(path: string): Promise<boolean> {
     .catch(() => false);
 }
 
+export async function isDirectory(filePath: string): Promise<boolean> {
+  try {
+    const stat = await fsP.stat(filePath);
+    return stat.isDirectory();
+  } catch {
+    return false;
+  }
+}
+
 export async function emptyDir(dir: string): Promise<void> {
   if (!(await pathExists(dir))) {
     return;
@@ -164,6 +173,27 @@ export async function addBannerAndFooter(
   }
 }
 
+async function addExtension(
+  redirect: DtsRedirect,
+  dtsFile: string,
+  path: string,
+  extension: string,
+): Promise<string> {
+  if (!redirect.extension) {
+    return path;
+  }
+
+  let redirectPath = path;
+
+  // If the import path refers to a directory, it most likely actually refers to a `index.*` file due to Node's module resolution
+  if (await isDirectory(join(dirname(dtsFile), redirectPath))) {
+    // This uses `/` instead of `path.join` here because `join` removes potential "./" prefixes
+    redirectPath = `${redirectPath}/index`;
+  }
+
+  return `${redirectPath}${extension}`;
+}
+
 export async function redirectDtsImports(
   dtsFile: string,
   dtsExtension: string,
@@ -218,7 +248,7 @@ export async function redirectDtsImports(
       e: matchNode.range().end.index,
     };
   });
-  const extensions = dtsExtension
+  const extension = dtsExtension
     .replace(/\.d\.ts$/, '.js')
     .replace(/\.d\.cts$/, '.cjs')
     .replace(/\.d\.mts$/, '.mjs');
@@ -269,7 +299,7 @@ export async function redirectDtsImports(
           if (redirect.extension) {
             redirectImportPath = redirectImportPath.replace(
               /\.[^.]+$/,
-              extensions,
+              extension,
             );
           }
         }
@@ -278,15 +308,21 @@ export async function redirectDtsImports(
           absoluteImportPath &&
           normalize(absoluteImportPath).startsWith(normalize(rootDir))
         ) {
-          if (redirect.extension) {
-            redirectImportPath = `${redirectImportPath}${extensions}`;
-          }
+          redirectImportPath = await addExtension(
+            redirect,
+            dtsFile,
+            redirectImportPath,
+            extension,
+          );
         }
 
         if (!absoluteImportPath && importPath.startsWith('.')) {
-          if (redirect.extension) {
-            redirectImportPath = `${redirectImportPath}${extensions}`;
-          }
+          redirectImportPath = await addExtension(
+            redirect,
+            dtsFile,
+            redirectImportPath,
+            extension,
+          );
         }
       }
 
diff --git a/tests/integration/redirect/dts.test.ts b/tests/integration/redirect/dts.test.ts
index 6633c1c30..9ddf0dcde 100644
--- a/tests/integration/redirect/dts.test.ts
+++ b/tests/integration/redirect/dts.test.ts
@@ -16,6 +16,8 @@ test('redirect.dts default', async () => {
     import { logger } from '../../../../compile/rslog';
     import { logRequest as logRequest2 } from '../logger';
     export { logRequest, logRequest2, logger };
+    ",
+      "<ROOT>/tests/integration/redirect/dts/dist/default/esm/foo/index.d.ts": "export type Barrel = string;
     ",
       "<ROOT>/tests/integration/redirect/dts/dist/default/esm/index.d.ts": "import { logRequest } from './logger';
     import { logger } from '../../../compile/rslog';
@@ -24,6 +26,8 @@ test('redirect.dts default', async () => {
     export { logRequest, logger, type LoggerOptions, defaultOptions };
     export type { Foo } from './types';
     export type { Bar } from './types';
+    export * from './foo';
+    export * from './foo';
     export * from './types';
     export * from '../../../compile/rslog';
     export * from './logger';
@@ -55,6 +59,8 @@ test('redirect.dts.path false', async () => {
     import { logger } from 'rslog';
     import { logRequest as logRequest2 } from '../logger';
     export { logRequest, logRequest2, logger };
+    ",
+      "<ROOT>/tests/integration/redirect/dts/dist/path-false/esm/foo/index.d.ts": "export type Barrel = string;
     ",
       "<ROOT>/tests/integration/redirect/dts/dist/path-false/esm/index.d.ts": "import { logRequest } from '@src/logger';
     import { logger } from 'rslog';
@@ -63,6 +69,8 @@ test('redirect.dts.path false', async () => {
     export { logRequest, logger, type LoggerOptions, defaultOptions };
     export type { Foo } from '@src/types';
     export type { Bar } from 'types';
+    export * from './foo';
+    export * from '@src/foo';
     export * from './types';
     export * from 'rslog';
     export * from '@src/logger';
@@ -94,6 +102,8 @@ test('redirect.dts.extension true', async () => {
     import { logger } from '../../../../compile/rslog';
     import { logRequest as logRequest2 } from '../logger.js';
     export { logRequest, logRequest2, logger };
+    ",
+      "<ROOT>/tests/integration/redirect/dts/dist/extension-true/esm/foo/index.d.ts": "export type Barrel = string;
     ",
       "<ROOT>/tests/integration/redirect/dts/dist/extension-true/esm/index.d.ts": "import { logRequest } from './logger.js';
     import { logger } from '../../../compile/rslog';
@@ -102,6 +112,8 @@ test('redirect.dts.extension true', async () => {
     export { logRequest, logger, type LoggerOptions, defaultOptions };
     export type { Foo } from './types.js';
     export type { Bar } from './types.js';
+    export * from './foo/index.js';
+    export * from './foo/index.js';
     export * from './types.js';
     export * from '../../../compile/rslog';
     export * from './logger.js';
@@ -133,6 +145,8 @@ test('redirect.dts.extension true with dts.autoExtension true', async () => {
     import { logger } from '../../../../compile/rslog';
     import { logRequest as logRequest2 } from '../logger.mjs';
     export { logRequest, logRequest2, logger };
+    ",
+      "<ROOT>/tests/integration/redirect/dts/dist/auto-extension-true/esm/foo/index.d.mts": "export type Barrel = string;
     ",
       "<ROOT>/tests/integration/redirect/dts/dist/auto-extension-true/esm/index.d.mts": "import { logRequest } from './logger.mjs';
     import { logger } from '../../../compile/rslog';
@@ -141,6 +155,8 @@ test('redirect.dts.extension true with dts.autoExtension true', async () => {
     export { logRequest, logger, type LoggerOptions, defaultOptions };
     export type { Foo } from './types.mjs';
     export type { Bar } from './types.mjs';
+    export * from './foo/index.mjs';
+    export * from './foo/index.mjs';
     export * from './types.mjs';
     export * from '../../../compile/rslog';
     export * from './logger.mjs';
diff --git a/tests/integration/redirect/dts/src/foo/index.ts b/tests/integration/redirect/dts/src/foo/index.ts
new file mode 100644
index 000000000..77a95f681
--- /dev/null
+++ b/tests/integration/redirect/dts/src/foo/index.ts
@@ -0,0 +1 @@
+export type Barrel = string;
diff --git a/tests/integration/redirect/dts/src/index.ts b/tests/integration/redirect/dts/src/index.ts
index a0a31097b..b4402c115 100644
--- a/tests/integration/redirect/dts/src/index.ts
+++ b/tests/integration/redirect/dts/src/index.ts
@@ -7,6 +7,8 @@ export { logRequest, logger, type LoggerOptions, defaultOptions };
 
 export type { Foo } from '@src/types';
 export type { Bar } from 'types';
+export * from './foo';
+export * from '@src/foo';
 export * from './types';
 export * from 'rslog';
 export * from '@src/logger';