diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
index 35dad3677c..94e4e506c3 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
@@ -220,4 +220,37 @@ bool is_valid_iso_date(i32 year, u8 month, u8 day)
     return true;
 }
 
+// 3.5.10 CompareISODate ( y1, m1, d1, y2, m2, d2 ), https://tc39.es/proposal-temporal/#sec-temporal-compareisodate
+i8 compare_iso_date(i32 year1, u8 month1, u8 day1, i32 year2, u8 month2, u8 day2)
+{
+    // 1. Assert: y1, m1, d1, y2, m2, and d2 are integers.
+
+    // 2. If y1 > y2, return 1.
+    if (year1 > year2)
+        return 1;
+
+    // 3. If y1 < y2, return -1.
+    if (year1 < year2)
+        return -1;
+
+    // 4. If m1 > m2, return 1.
+    if (month1 > month2)
+        return 1;
+
+    // 5. If m1 < m2, return -1.
+    if (month1 < month2)
+        return -1;
+
+    // 6. If d1 > d2, return 1.
+    if (day1 > day2)
+        return 1;
+
+    // 7. If d1 < d2, return -1.
+    if (day1 < day2)
+        return -1;
+
+    // 8. Return 0.
+    return 0;
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
index abc49edfca..aca9a99fbe 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
@@ -38,5 +38,6 @@ PlainDate* create_temporal_date(GlobalObject&, i32 iso_year, u8 iso_month, u8 is
 PlainDate* to_temporal_date(GlobalObject&, Value item, Object* options = nullptr);
 Optional<TemporalDate> regulate_iso_date(GlobalObject&, double year, double month, double day, String const& overflow);
 bool is_valid_iso_date(i32 year, u8 month, u8 day);
+i8 compare_iso_date(i32 year1, u8 month1, u8 day1, i32 year2, u8 month2, u8 day2);
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.cpp
index 1e5e056dae..b6f38b2d6b 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.cpp
@@ -27,6 +27,9 @@ void PlainDateConstructor::initialize(GlobalObject& global_object)
     // 3.2.1 Temporal.PlainDate.prototype, https://tc39.es/proposal-temporal/#sec-temporal-plaindate-prototype
     define_direct_property(vm.names.prototype, global_object.temporal_plain_date_prototype(), 0);
 
+    u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.compare, compare, 2, attr);
+
     define_direct_property(vm.names.length, Value(3), Attribute::Configurable);
 }
 
@@ -93,4 +96,19 @@ Value PlainDateConstructor::construct(FunctionObject& new_target)
     return create_temporal_date(global_object, y, m, d, *calendar, &new_target);
 }
 
+// 3.2.3 Temporal.PlainDate.compare ( one, two ), https://tc39.es/proposal-temporal/#sec-properties-of-the-temporal-plaindate-constructor
+JS_DEFINE_NATIVE_FUNCTION(PlainDateConstructor::compare)
+{
+    // 1. Set one to ? ToTemporalDate(one).
+    auto* one = to_temporal_date(global_object, vm.argument(0));
+    if (vm.exception())
+        return {};
+    // 2. Set two to ? ToTemporalDate(two).
+    auto* two = to_temporal_date(global_object, vm.argument(1));
+    if (vm.exception())
+        return {};
+    // 3. Return 𝔽(! CompareISODate(one.[[ISOYear]], one.[[ISOMonth]], one.[[ISODay]], two.[[ISOYear]], two.[[ISOMonth]], two.[[ISODay]])).
+    return Value(compare_iso_date(one->iso_year(), one->iso_month(), one->iso_day(), two->iso_year(), two->iso_month(), two->iso_day()));
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
index 830330412d..e02a3153c4 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateConstructor.h
@@ -23,6 +23,8 @@ public:
 
 private:
     virtual bool has_constructor() const override { return true; }
+
+    JS_DECLARE_NATIVE_FUNCTION(compare);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.compare.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.compare.js
new file mode 100644
index 0000000000..a6a92799a3
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDate/PlainDate.compare.js
@@ -0,0 +1,13 @@
+describe("correct behavior", () => {
+    test("length is 2", () => {
+        expect(Temporal.PlainDate.compare).toHaveLength(2);
+    });
+
+    test("basic functionality", () => {
+        const plainDate1 = new Temporal.PlainDate(2021, 7, 26);
+        expect(Temporal.PlainDate.compare(plainDate1, plainDate1)).toBe(0);
+        const plainDate2 = new Temporal.PlainDate(2021, 7, 27);
+        expect(Temporal.PlainDate.compare(plainDate1, plainDate2)).toBe(-1);
+        expect(Temporal.PlainDate.compare(plainDate2, plainDate1)).toBe(1);
+    });
+});