diff --git a/UPGRADE.md b/UPGRADE.md
index 0673dc70bf1..24d699e1371 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -1,5 +1,9 @@
 # Upgrade to 3.0
 
+## BC BREAK: `Doctrine\ORM\Proxy\Autoloader` no longer extends `Doctrine\Common\Proxy\Autoloader`
+
+Make sure to use the former when writing a type declaration or an `instanceof` check.
+
 ## Minor BC BREAK: Changed order of arguments passed to `OneToOne`, `ManyToOne` and `Index` mapping PHP attributes
 
 To keep PHP mapping attributes consistent, order of arguments passed to above attributes has been changed
@@ -328,10 +332,6 @@ Use `Doctrine\Persistence\Mapping\Driver\StaticPHPDriver` and
 The second argument to `UnderscoreNamingStrategy::__construct()` was dropped,
 the strategy can no longer be unaware of numbers.
 
-## BC BREAK: Remove `Doctrine\ORM\Proxy\Autoloader`
-
-Use `Doctrine\Common\Proxy\Autoloader` instead.
-
 ## BC BREAK: Remove `Doctrine\ORM\Tools\DisconnectedClassMetadataFactory`
 
 No replacement is provided.
diff --git a/composer.json b/composer.json
index ceae5193171..1064ebadeaf 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,6 @@
         "composer-runtime-api": "^2",
         "ext-ctype": "*",
         "doctrine/collections": "^2.1",
-        "doctrine/common": "^3.3",
         "doctrine/dbal": "^3.6 || ^4",
         "doctrine/deprecations": "^0.5.3 || ^1",
         "doctrine/event-manager": "^1.2 || ^2",
diff --git a/lib/Doctrine/ORM/Proxy/Autoloader.php b/lib/Doctrine/ORM/Proxy/Autoloader.php
new file mode 100644
index 00000000000..d30477a80e8
--- /dev/null
+++ b/lib/Doctrine/ORM/Proxy/Autoloader.php
@@ -0,0 +1,86 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ORM\Proxy;
+
+use Closure;
+
+use function file_exists;
+use function ltrim;
+use function spl_autoload_register;
+use function str_replace;
+use function strlen;
+use function strpos;
+use function substr;
+
+use const DIRECTORY_SEPARATOR;
+
+/**
+ * Special Autoloader for Proxy classes, which are not PSR-0 compliant.
+ */
+final class Autoloader
+{
+    /**
+     * Resolves proxy class name to a filename based on the following pattern.
+     *
+     * 1. Remove Proxy namespace from class name.
+     * 2. Remove namespace separators from remaining class name.
+     * 3. Return PHP filename from proxy-dir with the result from 2.
+     *
+     * @psalm-param class-string $className
+     *
+     * @throws NotAProxyClass
+     */
+    public static function resolveFile(string $proxyDir, string $proxyNamespace, string $className): string
+    {
+        if (strpos($className, $proxyNamespace) !== 0) {
+            throw new NotAProxyClass($className, $proxyNamespace);
+        }
+
+        // remove proxy namespace from class name
+        $classNameRelativeToProxyNamespace = substr($className, strlen($proxyNamespace));
+
+        // remove namespace separators from remaining class name
+        $fileName = str_replace('\\', '', $classNameRelativeToProxyNamespace);
+
+        return $proxyDir . DIRECTORY_SEPARATOR . $fileName . '.php';
+    }
+
+    /**
+     * Registers and returns autoloader callback for the given proxy dir and namespace.
+     *
+     * @param Closure(string, string, class-string): void|null $notFoundCallback Invoked when the proxy file is not found.
+     *
+     * @return Closure(string): void
+     */
+    public static function register(
+        string $proxyDir,
+        string $proxyNamespace,
+        Closure|null $notFoundCallback = null,
+    ): Closure {
+        $proxyNamespace = ltrim($proxyNamespace, '\\');
+
+        $autoloader = /** @param class-string $className */ static function (string $className) use ($proxyDir, $proxyNamespace, $notFoundCallback): void {
+            if ($proxyNamespace === '') {
+                return;
+            }
+
+            if (strpos($className, $proxyNamespace) !== 0) {
+                return;
+            }
+
+            $file = Autoloader::resolveFile($proxyDir, $proxyNamespace, $className);
+
+            if ($notFoundCallback && ! file_exists($file)) {
+                $notFoundCallback($proxyDir, $proxyNamespace, $className);
+            }
+
+            require $file;
+        };
+
+        spl_autoload_register($autoloader);
+
+        return $autoloader;
+    }
+}
diff --git a/lib/Doctrine/ORM/Proxy/NotAProxyClass.php b/lib/Doctrine/ORM/Proxy/NotAProxyClass.php
new file mode 100644
index 00000000000..689cc3e12dc
--- /dev/null
+++ b/lib/Doctrine/ORM/Proxy/NotAProxyClass.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\ORM\Proxy;
+
+use Doctrine\ORM\Exception\ORMException;
+use InvalidArgumentException;
+
+use function sprintf;
+
+final class NotAProxyClass extends InvalidArgumentException implements ORMException
+{
+    public function __construct(string $className, string $proxyNamespace)
+    {
+        parent::__construct(sprintf(
+            'The class "%s" is not part of the proxy namespace "%s"',
+            $className,
+            $proxyNamespace,
+        ));
+    }
+}
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index e0137cfe929..f2640271ae7 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -737,6 +737,20 @@
       <code>string</code>
     </MoreSpecificReturnType>
   </file>
+  <file src="lib/Doctrine/ORM/Proxy/Autoloader.php">
+    <ArgumentTypeCoercion>
+      <code>$autoloader</code>
+    </ArgumentTypeCoercion>
+    <LessSpecificReturnStatement>
+      <code>$autoloader</code>
+    </LessSpecificReturnStatement>
+    <MoreSpecificReturnType>
+      <code>Closure(string): void</code>
+    </MoreSpecificReturnType>
+    <UnresolvableInclude>
+      <code>require $file</code>
+    </UnresolvableInclude>
+  </file>
   <file src="lib/Doctrine/ORM/Proxy/ProxyFactory.php">
     <ArgumentTypeCoercion>
       <code>$classMetadata</code>
diff --git a/tests/Doctrine/Tests/Proxy/AutoloaderTest.php b/tests/Doctrine/Tests/Proxy/AutoloaderTest.php
new file mode 100644
index 00000000000..1bcf37910a2
--- /dev/null
+++ b/tests/Doctrine/Tests/Proxy/AutoloaderTest.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\Proxy;
+
+use Doctrine\ORM\Proxy\Autoloader;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+use function class_exists;
+use function file_exists;
+use function file_put_contents;
+use function sys_get_temp_dir;
+use function unlink;
+
+use const DIRECTORY_SEPARATOR;
+
+class AutoloaderTest extends TestCase
+{
+    /** @return iterable<string, array{string, string, class-string, string}> */
+    public static function dataResolveFile(): iterable
+    {
+        return [
+            ['/tmp', 'MyProxy', 'MyProxy\RealClass', '/tmp' . DIRECTORY_SEPARATOR . 'RealClass.php'],
+            ['/tmp', 'MyProxy', 'MyProxy\__CG__\RealClass', '/tmp' . DIRECTORY_SEPARATOR . '__CG__RealClass.php'],
+            ['/tmp', 'MyProxy\Subdir', 'MyProxy\Subdir\__CG__\RealClass', '/tmp' . DIRECTORY_SEPARATOR . '__CG__RealClass.php'],
+            ['/tmp', 'MyProxy', 'MyProxy\__CG__\Other\RealClass', '/tmp' . DIRECTORY_SEPARATOR . '__CG__OtherRealClass.php'],
+        ];
+    }
+
+    /** @param class-string $className */
+    #[DataProvider('dataResolveFile')]
+    public function testResolveFile(
+        string $proxyDir,
+        string $proxyNamespace,
+        string $className,
+        string $expectedProxyFile,
+    ): void {
+        $actualProxyFile = Autoloader::resolveFile($proxyDir, $proxyNamespace, $className);
+        self::assertEquals($expectedProxyFile, $actualProxyFile);
+    }
+
+    public function testAutoload(): void
+    {
+        if (file_exists(sys_get_temp_dir() . '/AutoloaderTestClass.php')) {
+            unlink(sys_get_temp_dir() . '/AutoloaderTestClass.php');
+        }
+
+        $autoloader = Autoloader::register(sys_get_temp_dir(), 'ProxyAutoloaderTest', static function ($proxyDir, $proxyNamespace, $className): void {
+            file_put_contents(sys_get_temp_dir() . '/AutoloaderTestClass.php', '<?php namespace ProxyAutoloaderTest; class AutoloaderTestClass {} ');
+        });
+
+        self::assertTrue(class_exists('ProxyAutoloaderTest\AutoloaderTestClass', true));
+        unlink(sys_get_temp_dir() . '/AutoloaderTestClass.php');
+    }
+}