diff --git a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
index 485968ccb6..95be6f7be9 100644
--- a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
+++ b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
@@ -246,6 +246,7 @@ namespace JS {
     P(multiline)                             \
     P(name)                                  \
     P(nanoseconds)                           \
+    P(negated)                               \
     P(next)                                  \
     P(now)                                   \
     P(of)                                    \
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.cpp
index cff8eb430a..1e8aa8942b 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.cpp
@@ -40,6 +40,7 @@ void DurationPrototype::initialize(GlobalObject& global_object)
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_function(vm.names.with, with, 1, attr);
+    define_native_function(vm.names.negated, negated, 0, attr);
     define_native_function(vm.names.valueOf, value_of, 0, attr);
 }
 
@@ -297,6 +298,19 @@ JS_DEFINE_NATIVE_FUNCTION(DurationPrototype::with)
     return create_temporal_duration(global_object, years, months, weeks, days, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);
 }
 
+// 7.3.16 Temporal.Duration.prototype.negated ( ), https://tc39.es/proposal-temporal/#sec-temporal.duration.prototype.negated
+JS_DEFINE_NATIVE_FUNCTION(DurationPrototype::negated)
+{
+    // 1. Let duration be the this value.
+    // 2. Perform ? RequireInternalSlot(duration, [[InitializedTemporalDuration]]).
+    auto* duration = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Return ? CreateTemporalDuration(−duration.[[Years]], −duration.[[Months]], −duration.[[Weeks]], −duration.[[Days]], −duration.[[Hours]], −duration.[[Minutes]], −duration.[[Seconds]], −duration.[[Milliseconds]], −duration.[[Microseconds]], −duration.[[Nanoseconds]]).
+    return create_temporal_duration(global_object, -duration->years(), -duration->months(), -duration->weeks(), -duration->days(), -duration->hours(), -duration->minutes(), -duration->seconds(), -duration->milliseconds(), -duration->microseconds(), -duration->nanoseconds());
+}
+
 // 7.3.25 Temporal.Duration.prototype.valueOf ( ), https://tc39.es/proposal-temporal/#sec-temporal.duration.prototype.valueof
 JS_DEFINE_NATIVE_FUNCTION(DurationPrototype::value_of)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
index 507b5c9c83..7d57107905 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/DurationPrototype.h
@@ -32,6 +32,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(sign_getter);
     JS_DECLARE_NATIVE_FUNCTION(blank_getter);
     JS_DECLARE_NATIVE_FUNCTION(with);
+    JS_DECLARE_NATIVE_FUNCTION(negated);
     JS_DECLARE_NATIVE_FUNCTION(value_of);
 };
 
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.negated.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.negated.js
new file mode 100644
index 0000000000..f62a07c368
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.negated.js
@@ -0,0 +1,42 @@
+const DURATION_PROPERTIES = [
+    "years",
+    "months",
+    "weeks",
+    "days",
+    "hours",
+    "minutes",
+    "seconds",
+    "milliseconds",
+    "microseconds",
+    "nanoseconds",
+];
+
+describe("correct behavior", () => {
+    test("length is 0", () => {
+        expect(Temporal.Duration.prototype.negated).toHaveLength(0);
+    });
+
+    test("basic functionality", () => {
+        const negativeDuration = new Temporal.Duration(123).negated();
+        expect(negativeDuration.years).toBe(-123);
+
+        const positiveDuration = new Temporal.Duration(-123).negated();
+        expect(positiveDuration.years).toBe(123);
+    });
+
+    test("each property is negated", () => {
+        const values = Array(DURATION_PROPERTIES.length).fill(1);
+        const duration = new Temporal.Duration(...values).negated();
+        for (const property of DURATION_PROPERTIES) {
+            expect(duration[property]).toBe(-1);
+        }
+    });
+});
+
+test("errors", () => {
+    test("this value must be a Temporal.Duration object", () => {
+        expect(() => {
+            Temporal.Duration.prototype.negated.call("foo");
+        }).toThrowWithMessage(TypeError, "Not a Temporal.Duration");
+    });
+});