diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.cpp
index 3ade1273de..4535502ab9 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.cpp
@@ -30,6 +30,9 @@ void InstantPrototype::initialize(GlobalObject& global_object)
 
     // 8.3.2 Temporal.Instant.prototype[ @@toStringTag ], https://tc39.es/proposal-temporal/#sec-temporal.instant.prototype-@@tostringtag
     define_direct_property(*vm.well_known_symbol_to_string_tag(), js_string(vm.heap(), "Temporal.Instant"), Attribute::Configurable);
+
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.valueOf, value_of, 0, attr);
 }
 
 static Instant* typed_this(GlobalObject& global_object)
@@ -118,4 +121,12 @@ JS_DEFINE_NATIVE_FUNCTION(InstantPrototype::epoch_nanoseconds_getter)
     return &ns;
 }
 
+// 8.3.16 Temporal.Instant.prototype.valueOf ( ), https://tc39.es/proposal-temporal/#sec-temporal.instant.prototype.valueof
+JS_DEFINE_NATIVE_FUNCTION(InstantPrototype::value_of)
+{
+    // 1. Throw a TypeError exception.
+    vm.throw_exception<TypeError>(global_object, ErrorType::Convert, "Temporal.Instant", "a primitive value");
+    return {};
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
index 1854c59fb1..1f81ad62a0 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/InstantPrototype.h
@@ -23,6 +23,8 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(epoch_milliseconds_getter);
     JS_DECLARE_NATIVE_FUNCTION(epoch_microseconds_getter);
     JS_DECLARE_NATIVE_FUNCTION(epoch_nanoseconds_getter);
+
+    JS_DECLARE_NATIVE_FUNCTION(value_of);
 };
 
 }