diff --git a/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp b/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp
index b22c18b6c7..03344f21ec 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.cpp
@@ -6,10 +6,27 @@
 
 #include <AK/TypeCasts.h>
 #include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Intl/Locale.h>
 #include <LibJS/Runtime/Intl/LocalePrototype.h>
 
 namespace JS::Intl {
 
+static Locale* typed_this(GlobalObject& global_object)
+{
+    auto& vm = global_object.vm();
+
+    auto* this_object = vm.this_value(global_object).to_object(global_object);
+    if (!this_object)
+        return nullptr;
+
+    if (!is<Locale>(this_object)) {
+        vm.throw_exception<TypeError>(global_object, ErrorType::NotA, "Intl.Locale");
+        return nullptr;
+    }
+
+    return static_cast<Locale*>(this_object);
+}
+
 // 14.3 Properties of the Intl.Locale Prototype Object, https://tc39.es/ecma402/#sec-properties-of-intl-locale-prototype-object
 LocalePrototype::LocalePrototype(GlobalObject& global_object)
     : Object(*global_object.object_prototype())
@@ -22,8 +39,24 @@ void LocalePrototype::initialize(GlobalObject& global_object)
 
     auto& vm = this->vm();
 
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.toString, to_string, 0, attr);
+
     // 14.3.2 Intl.Locale.prototype[ @@toStringTag ], https://tc39.es/ecma402/#sec-Intl.Locale.prototype-@@tostringtag
     define_direct_property(*vm.well_known_symbol_to_string_tag(), js_string(vm, "Intl.Locale"), Attribute::Configurable);
 }
 
+// 14.3.5 Intl.Locale.prototype.toString ( ), https://tc39.es/ecma402/#sec-Intl.Locale.prototype.toString
+JS_DEFINE_NATIVE_FUNCTION(LocalePrototype::to_string)
+{
+    // 1. Let loc be the this value.
+    // 2. Perform ? RequireInternalSlot(loc, [[InitializedLocale]]).
+    auto* locale_object = typed_this(global_object);
+    if (!locale_object)
+        return {};
+
+    // 3. Return loc.[[Locale]].
+    return js_string(vm, locale_object->locale());
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.h b/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
index 46b956ebe3..21de9dabd7 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Intl/LocalePrototype.h
@@ -17,6 +17,9 @@ public:
     explicit LocalePrototype(GlobalObject&);
     virtual void initialize(GlobalObject&) override;
     virtual ~LocalePrototype() override = default;
+
+private:
+    JS_DECLARE_NATIVE_FUNCTION(to_string);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Intl/Locale/Locale.prototype.toString.js b/Userland/Libraries/LibJS/Tests/builtins/Intl/Locale/Locale.prototype.toString.js
new file mode 100644
index 0000000000..caeac0c9ac
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Intl/Locale/Locale.prototype.toString.js
@@ -0,0 +1,3 @@
+test("length is 0", () => {
+    expect(Intl.Locale.prototype.toString).toHaveLength(0);
+});