diff --git a/src/LiveComponent/src/Hydration/DoctrineEntityHydrationExtension.php b/src/LiveComponent/src/Hydration/DoctrineEntityHydrationExtension.php
index 43b6400d97c..53f6b0be7a9 100644
--- a/src/LiveComponent/src/Hydration/DoctrineEntityHydrationExtension.php
+++ b/src/LiveComponent/src/Hydration/DoctrineEntityHydrationExtension.php
@@ -48,8 +48,8 @@ public function hydrate(mixed $value, string $className): ?object
             return null;
         }
 
-        // $data is the single identifier or array of identifiers
-        if (\is_scalar($value) || (\is_array($value) && isset($value[0]))) {
+        // $data is a single identifier or array of identifiers
+        if (\is_scalar($value) || \is_array($value)) {
             return $this->objectManagerFor($className)->find($className, $value);
         }
 
@@ -64,6 +64,9 @@ public function dehydrate(object $object): mixed
             ->getIdentifierValues($object)
         ;
 
+        // Dehydrate ID values in case they are other entities
+        $id = array_map(fn ($id) => \is_object($id) && $this->supports($id::class) ? $this->dehydrate($id) : $id, $id);
+
         switch (\count($id)) {
             case 0:
                 // a non-persisted entity
diff --git a/src/LiveComponent/tests/Fixtures/Entity/CompositeIdEntity.php b/src/LiveComponent/tests/Fixtures/Entity/CompositeIdEntity.php
new file mode 100644
index 00000000000..5ac7a9d460a
--- /dev/null
+++ b/src/LiveComponent/tests/Fixtures/Entity/CompositeIdEntity.php
@@ -0,0 +1,29 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\LiveComponent\Tests\Fixtures\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+
+#[ORM\Entity]
+class CompositeIdEntity
+{
+    public function __construct(
+        #[ORM\Id]
+        #[ORM\Column(type: 'integer')]
+        private int $firstIdPart,
+
+        #[ORM\Id]
+        #[ORM\Column(type: 'integer')]
+        private int $secondIdPart,
+    ) {
+    }
+}
diff --git a/src/LiveComponent/tests/Fixtures/Entity/ForeignKeyIdEntity.php b/src/LiveComponent/tests/Fixtures/Entity/ForeignKeyIdEntity.php
new file mode 100644
index 00000000000..85aeb0a02b4
--- /dev/null
+++ b/src/LiveComponent/tests/Fixtures/Entity/ForeignKeyIdEntity.php
@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\LiveComponent\Tests\Fixtures\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+
+#[ORM\Entity]
+class ForeignKeyIdEntity
+{
+    public function __construct(
+        #[ORM\Id]
+        #[ORM\ManyToOne(cascade: ['persist'])]
+        public Entity1 $id,
+    ) {
+    }
+}
diff --git a/src/LiveComponent/tests/Fixtures/Factory/CompositeIdEntityFactory.php b/src/LiveComponent/tests/Fixtures/Factory/CompositeIdEntityFactory.php
new file mode 100644
index 00000000000..7cdf882da60
--- /dev/null
+++ b/src/LiveComponent/tests/Fixtures/Factory/CompositeIdEntityFactory.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\LiveComponent\Tests\Fixtures\Factory;
+
+use Doctrine\ORM\EntityRepository;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Entity\CompositeIdEntity;
+use Zenstruck\Foundry\ModelFactory;
+use Zenstruck\Foundry\Proxy;
+use Zenstruck\Foundry\RepositoryProxy;
+
+/**
+ * @extends ModelFactory<CompositeIdEntity>
+ *
+ * @method static CompositeIdEntity|Proxy          createOne(array $attributes = [])
+ * @method static CompositeIdEntity[]|Proxy[]      createMany(int $number, array|callable $attributes = [])
+ * @method static CompositeIdEntity|Proxy          find(object|array|mixed $criteria)
+ * @method static CompositeIdEntity|Proxy          findOrCreate(array $attributes)
+ * @method static CompositeIdEntity|Proxy          first(string $sortedField = 'id')
+ * @method static CompositeIdEntity|Proxy          last(string $sortedField = 'id')
+ * @method static CompositeIdEntity|Proxy          random(array $attributes = [])
+ * @method static CompositeIdEntity|Proxy          randomOrCreate(array $attributes = []))
+ * @method static CompositeIdEntity[]|Proxy[]      all()
+ * @method static CompositeIdEntity[]|Proxy[]      findBy(array $attributes)
+ * @method static CompositeIdEntity[]|Proxy[]      randomSet(int $number, array $attributes = []))
+ * @method static CompositeIdEntity[]|Proxy[]      randomRange(int $min, int $max, array $attributes = []))
+ * @method static EntityRepository|RepositoryProxy repository()
+ * @method        CompositeIdEntity|Proxy          create(array|callable $attributes = [])
+ */
+class CompositeIdEntityFactory extends ModelFactory
+{
+    protected static function getClass(): string
+    {
+        return CompositeIdEntity::class;
+    }
+
+    protected function getDefaults(): array
+    {
+        return [
+            'firstIdPart' => rand(1, \PHP_INT_MAX),
+            'secondIdPart' => rand(1, \PHP_INT_MAX),
+        ];
+    }
+}
diff --git a/src/LiveComponent/tests/Fixtures/Factory/ForeignKeyIdEntityFactory.php b/src/LiveComponent/tests/Fixtures/Factory/ForeignKeyIdEntityFactory.php
new file mode 100644
index 00000000000..ba5f9ac537d
--- /dev/null
+++ b/src/LiveComponent/tests/Fixtures/Factory/ForeignKeyIdEntityFactory.php
@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\LiveComponent\Tests\Fixtures\Factory;
+
+use Doctrine\ORM\EntityRepository;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Entity\Entity1;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Entity\ForeignKeyIdEntity;
+use Zenstruck\Foundry\ModelFactory;
+use Zenstruck\Foundry\Proxy;
+use Zenstruck\Foundry\RepositoryProxy;
+
+use function Zenstruck\Foundry\lazy;
+
+/**
+ * @extends ModelFactory<ForeignKeyIdEntity>
+ *
+ * @method static ForeignKeyIdEntity|Proxy         createOne(array $attributes = [])
+ * @method static ForeignKeyIdEntity[]|Proxy[]     createMany(int $number, array|callable $attributes = [])
+ * @method static ForeignKeyIdEntity|Proxy         find(object|array|mixed $criteria)
+ * @method static ForeignKeyIdEntity|Proxy         findOrCreate(array $attributes)
+ * @method static ForeignKeyIdEntity|Proxy         first(string $sortedField = 'id')
+ * @method static ForeignKeyIdEntity|Proxy         last(string $sortedField = 'id')
+ * @method static ForeignKeyIdEntity|Proxy         random(array $attributes = [])
+ * @method static ForeignKeyIdEntity|Proxy         randomOrCreate(array $attributes = []))
+ * @method static ForeignKeyIdEntity[]|Proxy[]     all()
+ * @method static ForeignKeyIdEntity[]|Proxy[]     findBy(array $attributes)
+ * @method static ForeignKeyIdEntity[]|Proxy[]     randomSet(int $number, array $attributes = []))
+ * @method static ForeignKeyIdEntity[]|Proxy[]     randomRange(int $min, int $max, array $attributes = []))
+ * @method static EntityRepository|RepositoryProxy repository()
+ * @method        ForeignKeyIdEntity|Proxy         create(array|callable $attributes = [])
+ */
+class ForeignKeyIdEntityFactory extends ModelFactory
+{
+    protected static function getClass(): string
+    {
+        return ForeignKeyIdEntity::class;
+    }
+
+    protected function getDefaults(): array
+    {
+        return ['id' => lazy(static fn () => new Entity1())];
+    }
+}
diff --git a/src/LiveComponent/tests/Integration/Hydration/DoctrineEntityHydrationExtensionTest.php b/src/LiveComponent/tests/Integration/Hydration/DoctrineEntityHydrationExtensionTest.php
new file mode 100644
index 00000000000..ff7b60ca04e
--- /dev/null
+++ b/src/LiveComponent/tests/Integration/Hydration/DoctrineEntityHydrationExtensionTest.php
@@ -0,0 +1,53 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\UX\LiveComponent\Tests\Unit\Hydration;
+
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+use Symfony\UX\LiveComponent\Hydration\DoctrineEntityHydrationExtension;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Entity\CompositeIdEntity;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Entity\ForeignKeyIdEntity;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Factory\CompositeIdEntityFactory;
+use Symfony\UX\LiveComponent\Tests\Fixtures\Factory\ForeignKeyIdEntityFactory;
+use Zenstruck\Foundry\Test\Factories;
+use Zenstruck\Foundry\Test\ResetDatabase;
+
+class DoctrineEntityHydrationExtensionTest extends KernelTestCase
+{
+    use Factories;
+    use ResetDatabase;
+
+    public function testCompositeId(): void
+    {
+        $compositeIdEntity = CompositeIdEntityFactory::createOne()->save()->object();
+
+        /** @var DoctrineEntityHydrationExtension $extension */
+        $extension = self::getContainer()->get('ux.live_component.doctrine_entity_hydration_extension');
+
+        self::assertSame(
+            $compositeIdEntity,
+            $extension->hydrate($extension->dehydrate($compositeIdEntity), CompositeIdEntity::class)
+        );
+    }
+
+    public function testForeignKeyId(): void
+    {
+        $foreignKeyIdEntity = ForeignKeyIdEntityFactory::createOne()->save()->object();
+
+        /** @var DoctrineEntityHydrationExtension $extension */
+        $extension = self::getContainer()->get('ux.live_component.doctrine_entity_hydration_extension');
+
+        $dehydrated = $extension->dehydrate($foreignKeyIdEntity);
+
+        self::assertSame($foreignKeyIdEntity->id->id, $dehydrated);
+        self::assertSame($foreignKeyIdEntity, $extension->hydrate($dehydrated, ForeignKeyIdEntity::class));
+    }
+}