diff --git a/src/Mapping/ClassMetadataFactory.php b/src/Mapping/ClassMetadataFactory.php
index 8ac89471359..cc37e618a80 100644
--- a/src/Mapping/ClassMetadataFactory.php
+++ b/src/Mapping/ClassMetadataFactory.php
@@ -34,6 +34,7 @@
 use function explode;
 use function in_array;
 use function is_a;
+use function is_int;
 use function is_subclass_of;
 use function method_exists;
 use function str_contains;
@@ -523,6 +524,17 @@ private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $par
         foreach (['uniqueConstraints', 'indexes'] as $indexType) {
             if (isset($parentClass->table[$indexType])) {
                 foreach ($parentClass->table[$indexType] as $indexName => $index) {
+                    if (is_int($indexName)) {
+                        // Unnamed indices only have a positional key, so identify them by
+                        // their columns: the inheriting table overrides such an index by
+                        // declaring one on the same columns
+                        if (! self::hasIndexOnSameColumns($subClass->table[$indexType] ?? [], $index)) {
+                            $subClass->table[$indexType][] = $index;
+                        }
+
+                        continue;
+                    }
+
                     if (isset($subClass->table[$indexType][$indexName])) {
                         continue; // Let the inheriting table override indices
                     }
@@ -533,6 +545,24 @@ private function addInheritedIndexes(ClassMetadata $subClass, ClassMetadata $par
         }
     }
 
+    /**
+     * @param array<int|string, array<string, mixed>> $indexes
+     * @param array<string, mixed>                    $index
+     */
+    private static function hasIndexOnSameColumns(array $indexes, array $index): bool
+    {
+        foreach ($indexes as $existingIndex) {
+            if (
+                ($existingIndex['columns'] ?? null) === ($index['columns'] ?? null)
+                && ($existingIndex['fields'] ?? null) === ($index['fields'] ?? null)
+            ) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /**
      * Completes the ID generator mapping. If "auto" is specified we choose the generator
      * most appropriate for the targeted database platform.
diff --git a/tests/Tests/ORM/Mapping/BasicInheritanceMappingTest.php b/tests/Tests/ORM/Mapping/BasicInheritanceMappingTest.php
index 097fb642428..efbbf5a92ab 100644
--- a/tests/Tests/ORM/Mapping/BasicInheritanceMappingTest.php
+++ b/tests/Tests/ORM/Mapping/BasicInheritanceMappingTest.php
@@ -187,6 +187,61 @@ public function testMappedSuperclassIndex(): void
         self::assertArrayHasKey('IDX_MAPPED2_INDEX', $class->table['indexes']);
     }
 
+    /**
+     * Ensure unnamed indexes are inherited from the mapped superclass
+     * even when the entity declares unnamed indexes of its own.
+     */
+    #[Group('GH-12179')]
+    public function testMappedSuperclassUnnamedIndexes(): void
+    {
+        $class = $this->cmf->getMetadataFor(EntityUnnamedIndexSubClass::class);
+        assert($class instanceof ClassMetadata);
+
+        self::assertSame(
+            [
+                ['columns' => ['name']],
+                ['columns' => ['mapped1']],
+            ],
+            $class->table['uniqueConstraints'],
+        );
+
+        // The indexes on mapped3 and mapped4 are declared by both classes: they must not be duplicated
+        self::assertSame(
+            [
+                ['columns' => ['code']],
+                ['columns' => ['mapped3']],
+                ['fields' => ['mapped4']],
+                ['columns' => ['mapped2']],
+            ],
+            $class->table['indexes'],
+        );
+    }
+
+    /**
+     * Ensure a named index of the entity replaces an unnamed index of the
+     * mapped superclass on the same columns instead of duplicating it.
+     */
+    #[Group('GH-12179')]
+    public function testMappedSuperclassUnnamedIndexOverriddenByNamedIndex(): void
+    {
+        $class = $this->cmf->getMetadataFor(EntityNamedIndexSubClass::class);
+        assert($class instanceof ClassMetadata);
+
+        self::assertSame(
+            [['columns' => ['mapped1']]],
+            $class->table['uniqueConstraints'],
+        );
+
+        self::assertSame(
+            [
+                'IDX_MAPPED2' => ['columns' => ['mapped2']],
+                0 => ['columns' => ['mapped3']],
+                1 => ['fields' => ['mapped4']],
+            ],
+            $class->table['indexes'],
+        );
+    }
+
     #[DataProvider('invalidHierarchyDeclarationClasses')]
     public function testUndeclaredHierarchyRejection(string $rootEntity, string $childClass): void
     {
@@ -318,6 +373,53 @@ class EntityIndexSubClass extends MappedSuperclassBaseIndex
     private string $name;
 }
 
+#[Table]
+#[UniqueConstraint(columns: ['mapped1'])]
+#[Index(columns: ['mapped2'])]
+#[Index(columns: ['mapped3'])]
+#[Index(fields: ['mapped4'])]
+#[MappedSuperclass]
+class MappedSuperclassBaseUnnamedIndex
+{
+    #[Column(type: 'string', length: 255)]
+    private string $mapped1;
+    #[Column(type: 'string', length: 255)]
+    private string $mapped2;
+    #[Column(type: 'string', length: 255)]
+    private string $mapped3;
+    #[Column(type: 'string', length: 255)]
+    private string $mapped4;
+}
+
+#[Table]
+#[UniqueConstraint(columns: ['name'])]
+#[Index(columns: ['code'])]
+#[Index(columns: ['mapped3'])]
+#[Index(fields: ['mapped4'])]
+#[Entity]
+class EntityUnnamedIndexSubClass extends MappedSuperclassBaseUnnamedIndex
+{
+    #[Id]
+    #[Column(type: 'integer')]
+    private int $id;
+
+    #[Column(type: 'string', length: 255)]
+    private string $name;
+
+    #[Column(type: 'string', length: 255)]
+    private string $code;
+}
+
+#[Table]
+#[Index(name: 'IDX_MAPPED2', columns: ['mapped2'])]
+#[Entity]
+class EntityNamedIndexSubClass extends MappedSuperclassBaseUnnamedIndex
+{
+    #[Id]
+    #[Column(type: 'integer')]
+    private int $id;
+}
+
 #[Entity]
 #[InheritanceType('SINGLE_TABLE')]
 #[DiscriminatorColumn(name: 'type', type: 'string', length: 20)]