diff --git a/cli/dts/lib.deno.ns.d.ts b/cli/dts/lib.deno.ns.d.ts
index 6b4e75bfa6..ddbb890b7e 100644
--- a/cli/dts/lib.deno.ns.d.ts
+++ b/cli/dts/lib.deno.ns.d.ts
@@ -1467,7 +1467,7 @@ declare namespace Deno {
    * Requires `allow-read` permission for the target path.
    * Also requires `allow-read` permission for the CWD if the target path is
    * relative.*/
-  export function realPathSync(path: string): string;
+  export function realPathSync(path: string | URL): string;
 
   /** Resolves to the absolute normalized path, with symbolic links resolved.
    *
@@ -1483,7 +1483,7 @@ declare namespace Deno {
    * Requires `allow-read` permission for the target path.
    * Also requires `allow-read` permission for the CWD if the target path is
    * relative.*/
-  export function realPath(path: string): Promise<string>;
+  export function realPath(path: string | URL): Promise<string>;
 
   export interface DirEntry {
     name: string;
diff --git a/cli/tests/unit/real_path_test.ts b/cli/tests/unit/real_path_test.ts
index fce28d80b5..10e060578c 100644
--- a/cli/tests/unit/real_path_test.ts
+++ b/cli/tests/unit/real_path_test.ts
@@ -1,9 +1,11 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 import {
   assert,
+  assertEquals,
   assertMatch,
   assertThrows,
   assertThrowsAsync,
+  pathToAbsoluteFileUrl,
   unitTest,
 } from "./test_util.ts";
 
@@ -19,6 +21,12 @@ unitTest({ perms: { read: true } }, function realPathSyncSuccess(): void {
   }
 });
 
+unitTest({ perms: { read: true } }, function realPathSyncUrl(): void {
+  const relative = "cli/tests/fixture.json";
+  const url = pathToAbsoluteFileUrl(relative);
+  assertEquals(Deno.realPathSync(relative), Deno.realPathSync(url));
+});
+
 unitTest(
   {
     perms: { read: true, write: true },
@@ -66,6 +74,15 @@ unitTest({ perms: { read: true } }, async function realPathSuccess(): Promise<
   }
 });
 
+unitTest(
+  { perms: { read: true } },
+  async function realPathUrl(): Promise<void> {
+    const relative = "cli/tests/fixture.json";
+    const url = pathToAbsoluteFileUrl(relative);
+    assertEquals(await Deno.realPath(relative), await Deno.realPath(url));
+  },
+);
+
 unitTest(
   {
     perms: { read: true, write: true },
diff --git a/runtime/js/30_fs.js b/runtime/js/30_fs.js
index 72126e6bbb..67c3d4a1fc 100644
--- a/runtime/js/30_fs.js
+++ b/runtime/js/30_fs.js
@@ -128,11 +128,11 @@
   }
 
   function realPathSync(path) {
-    return core.opSync("op_realpath_sync", path);
+    return core.opSync("op_realpath_sync", pathFromURL(path));
   }
 
   function realPath(path) {
-    return core.opAsync("op_realpath_async", path);
+    return core.opAsync("op_realpath_async", pathFromURL(path));
   }
 
   function removeSync(