diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
index 206d0d7adc..8e7efbbd77 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
@@ -2279,6 +2279,7 @@ static void generate_prototype_or_global_mixin_definitions(IDL::Interface const&
     auto is_global_interface = interface.extended_attributes.contains("Global");
     auto class_name = is_global_interface ? interface.global_mixin_class : interface.prototype_class;
     generator.set("name", interface.name);
+    generator.set("namespaced_name", interface.namespaced_name);
     generator.set("class_name", class_name);
     generator.set("fully_qualified_name", interface.fully_qualified_name);
 
@@ -2421,7 +2422,7 @@ JS::ThrowCompletionOr<void> @class_name@::initialize(JS::Realm& realm)
     }
 
     generator.append(R"~~~(
-    define_direct_property(*vm.well_known_symbol_to_string_tag(), MUST_OR_THROW_OOM(JS::PrimitiveString::create(vm, "@name@"sv)), JS::Attribute::Configurable);
+    define_direct_property(*vm.well_known_symbol_to_string_tag(), MUST_OR_THROW_OOM(JS::PrimitiveString::create(vm, "@namespaced_name@"sv)), JS::Attribute::Configurable);
 )~~~");
 
     if (!is_global_interface) {
@@ -2460,7 +2461,7 @@ static JS::ThrowCompletionOr<@fully_qualified_name@*> impl_from(JS::VM& vm)
 
         generator.append(R"~~~(
     if (!is<@fully_qualified_name@>(this_object))
-        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "@name@");
+        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "@namespaced_name@");
     return static_cast<@fully_qualified_name@*>(this_object);
 }
 )~~~");
@@ -2560,7 +2561,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@attribute.setter_callback@)
 {
     auto this_value = vm.this_value();
     if (!this_value.is_object() || !is<@fully_qualified_name@>(this_value.as_object()))
-        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "@name@");
+        return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "@namespaced_name@");
     TRY(this_value.as_object().internal_define_own_property("@attribute.name@", JS::PropertyDescriptor { .value = vm.argument(0), .writable = true }));
     return JS::js_undefined();
 }
@@ -2877,6 +2878,7 @@ void generate_constructor_implementation(IDL::Interface const& interface, String
     SourceGenerator generator { builder };
 
     generator.set("name", interface.name);
+    generator.set("namespaced_name", interface.namespaced_name);
     generator.set("prototype_class", interface.prototype_class);
     generator.set("constructor_class", interface.constructor_class);
     generator.set("fully_qualified_name", interface.fully_qualified_name);
@@ -2973,7 +2975,7 @@ namespace Web::Bindings {
 
 JS::ThrowCompletionOr<JS::Value> @constructor_class@::call()
 {
-    return vm().throw_completion<JS::TypeError>(JS::ErrorType::ConstructorWithoutNew, "@name@");
+    return vm().throw_completion<JS::TypeError>(JS::ErrorType::ConstructorWithoutNew, "@namespaced_name@");
 }
 
 JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> @constructor_class@::construct(FunctionObject&)
@@ -2984,7 +2986,7 @@ JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> @constructor_class@::constru
         // No constructor
         generator.set("constructor.length", "0");
         generator.append(R"~~~(
-    return vm().throw_completion<JS::TypeError>(JS::ErrorType::NotAConstructor, "@name@");
+    return vm().throw_completion<JS::TypeError>(JS::ErrorType::NotAConstructor, "@namespaced_name@");
 )~~~");
     } else if (interface.constructors.size() == 1) {
         // Single constructor
@@ -3029,7 +3031,7 @@ JS::ThrowCompletionOr<void> @constructor_class@::initialize(JS::Realm& realm)
     [[maybe_unused]] u8 default_attributes = JS::Attribute::Enumerable;
 
     MUST_OR_THROW_OOM(Base::initialize(realm));
-    define_direct_property(vm.names.prototype, &ensure_web_prototype<@prototype_class@>(realm, "@name@"), 0);
+    define_direct_property(vm.names.prototype, &ensure_web_prototype<@prototype_class@>(realm, "@namespaced_name@"), 0);
     define_direct_property(vm.names.length, JS::Value(@constructor.length@), JS::Attribute::Configurable);
 
 )~~~");
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
index 8c44a6a92f..0b9b6fa7a4 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
@@ -225,7 +225,7 @@ void Intrinsics::create_web_prototype_and_constructor<@prototype_class@>(JS::Rea
         if (interface.is_namespace)
             add_namespace(gen, interface.name, interface.namespace_class);
         else
-            add_interface(gen, interface.name, interface.prototype_class, interface.constructor_class, lookup_legacy_constructor(interface));
+            add_interface(gen, interface.namespaced_name, interface.prototype_class, interface.constructor_class, lookup_legacy_constructor(interface));
     }
 
     // FIXME: Special case WebAssembly. We should convert WASM to use IDL.
@@ -346,7 +346,7 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
         if (interface.is_namespace)
             add_namespace(gen, interface.name, interface.namespace_class);
         else
-            add_interface(gen, interface.name, interface.prototype_class, lookup_legacy_constructor(interface));
+            add_interface(gen, interface.namespaced_name, interface.prototype_class, lookup_legacy_constructor(interface));
     }
 
     generator.append(R"~~~(
diff --git a/Userland/Libraries/LibIDL/IDLParser.cpp b/Userland/Libraries/LibIDL/IDLParser.cpp
index 0e3683fcb9..0470c87fdb 100644
--- a/Userland/Libraries/LibIDL/IDLParser.cpp
+++ b/Userland/Libraries/LibIDL/IDLParser.cpp
@@ -592,6 +592,11 @@ void Parser::parse_interface(Interface& interface)
         parse_function(extended_attributes, interface);
     }
 
+    if (auto legacy_namespace = interface.extended_attributes.get("LegacyNamespace"sv); legacy_namespace.has_value())
+        interface.namespaced_name = DeprecatedString::formatted("{}.{}", *legacy_namespace, interface.name);
+    else
+        interface.namespaced_name = interface.name;
+
     interface.constructor_class = DeprecatedString::formatted("{}Constructor", interface.name);
     interface.prototype_class = DeprecatedString::formatted("{}Prototype", interface.name);
     interface.prototype_base_class = DeprecatedString::formatted("{}Prototype", interface.parent_name.is_empty() ? "Object" : interface.parent_name);
diff --git a/Userland/Libraries/LibIDL/Types.h b/Userland/Libraries/LibIDL/Types.h
index dab0884e47..a471fb0aca 100644
--- a/Userland/Libraries/LibIDL/Types.h
+++ b/Userland/Libraries/LibIDL/Types.h
@@ -255,6 +255,7 @@ public:
 
     DeprecatedString name;
     DeprecatedString parent_name;
+    DeprecatedString namespaced_name;
 
     bool is_namespace { false };
     bool is_mixin { false };