diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.cpp
index 9401e548a8..5670e626bd 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.cpp
@@ -58,6 +58,7 @@ void PlainDateTimePrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.eraYear, era_year_getter, {}, Attribute::Configurable);
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.with, with, 1, attr);
     define_native_function(vm.names.withPlainTime, with_plain_time, 1, attr);
     define_native_function(vm.names.withPlainDate, with_plain_date, 1, attr);
     define_native_function(vm.names.withCalendar, with_calendar, 1, attr);
@@ -350,6 +351,58 @@ JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::era_year_getter)
     return TRY(calendar_era_year(global_object, calendar, *plain_date_time));
 }
 
+// 5.3.22 Temporal.PlainDateTime.prototype.with ( temporalDateTimeLike [ , options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.with
+JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::with)
+{
+    auto temporal_date_time_like = vm.argument(0);
+
+    // 1. Let dateTime be the this value.
+    // 2. Perform ? RequireInternalSlot(dateTime, [[InitializedTemporalDateTime]]).
+    auto* date_time = TRY(typed_this_object(global_object));
+
+    // 3. If Type(temporalDateTimeLike) is not Object, then
+    if (!temporal_date_time_like.is_object()) {
+        // a. Throw a TypeError exception.
+        return vm.throw_completion<TypeError>(global_object, ErrorType::NotAnObject, temporal_date_time_like.to_string_without_side_effects());
+    }
+
+    // 4. Perform ? RejectObjectWithCalendarOrTimeZone(temporalDateTimeLike).
+    TRY(reject_object_with_calendar_or_time_zone(global_object, temporal_date_time_like.as_object()));
+
+    // 5. Let calendar be dateTime.[[Calendar]].
+    auto& calendar = date_time->calendar();
+
+    // 6. Let fieldNames be ? CalendarFields(calendar, « "day", "hour", "microsecond", "millisecond", "minute", "month", "monthCode", "nanosecond", "second", "year" »).
+    auto field_names = TRY(calendar_fields(global_object, calendar, { "day"sv, "hour"sv, "microsecond"sv, "millisecond"sv, "minute"sv, "month"sv, "monthCode"sv, "nanosecond"sv, "second"sv, "year"sv }));
+
+    // 7. Let partialDateTime be ? PreparePartialTemporalFields(temporalDateTimeLike, fieldNames).
+    auto* partial_date_time = TRY(prepare_partial_temporal_fields(global_object, temporal_date_time_like.as_object(), field_names));
+
+    // 8. Set options to ? GetOptionsObject(options).
+    auto* options = TRY(get_options_object(global_object, vm.argument(1)));
+
+    // 9. Let fields be ? PrepareTemporalFields(dateTime, fieldNames, «»).
+    auto* fields = TRY(prepare_temporal_fields(global_object, *date_time, field_names, {}));
+
+    // 10. Set fields to ? CalendarMergeFields(calendar, fields, partialDateTime).
+    fields = TRY(calendar_merge_fields(global_object, calendar, *fields, *partial_date_time));
+
+    // 11. Set fields to ? PrepareTemporalFields(fields, fieldNames, «»).
+    fields = TRY(prepare_temporal_fields(global_object, *fields, field_names, {}));
+
+    // 12. Let result be ? InterpretTemporalDateTimeFields(calendar, fields, options).
+    auto result = TRY(interpret_temporal_date_time_fields(global_object, calendar, *fields, *options));
+
+    // 13. Assert: ! IsValidISODate(result.[[Year]], result.[[Month]], result.[[Day]]) is true.
+    VERIFY(is_valid_iso_date(result.year, result.month, result.day));
+
+    // 14. Assert: ! IsValidTime(result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]]) is true.
+    VERIFY(is_valid_time(result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond));
+
+    // 15. Return ? CreateTemporalDateTime(result.[[Year]], result.[[Month]], result.[[Day]], result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]], calendar).
+    return TRY(create_temporal_date_time(global_object, result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond, calendar));
+}
+
 // 5.3.23 Temporal.PlainDateTime.prototype.withPlainTime ( [ plainTimeLike ] ), https://tc39.es/proposal-temporal/#sec-temporal.plaindatetime.prototype.withplaintime
 JS_DEFINE_NATIVE_FUNCTION(PlainDateTimePrototype::with_plain_time)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
index 123f9d6186..6e10cd8f28 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDateTimePrototype.h
@@ -41,6 +41,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(in_leap_year_getter);
     JS_DECLARE_NATIVE_FUNCTION(era_getter);
     JS_DECLARE_NATIVE_FUNCTION(era_year_getter);
+    JS_DECLARE_NATIVE_FUNCTION(with);
     JS_DECLARE_NATIVE_FUNCTION(with_plain_time);
     JS_DECLARE_NATIVE_FUNCTION(with_plain_date);
     JS_DECLARE_NATIVE_FUNCTION(with_calendar);
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDateTime/PlainDateTime.prototype.with.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDateTime/PlainDateTime.prototype.with.js
new file mode 100644
index 0000000000..0bf57c6de7
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainDateTime/PlainDateTime.prototype.with.js
@@ -0,0 +1,86 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainDateTime.prototype.with).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const plainDateTime = new Temporal.PlainDateTime(1970, 1, 1);
+        const values = [
+            [{ year: 2021 }, new Temporal.PlainDateTime(2021, 1, 1)],
+            [{ year: 2021, month: 7 }, new Temporal.PlainDateTime(2021, 7, 1)],
+            [{ year: 2021, month: 7, day: 6 }, new Temporal.PlainDateTime(2021, 7, 6)],
+            [{ year: 2021, monthCode: "M07", day: 6 }, new Temporal.PlainDateTime(2021, 7, 6)],
+            [
+                { hour: 18, minute: 14, second: 47 },
+                new Temporal.PlainDateTime(1970, 1, 1, 18, 14, 47),
+            ],
+            [
+                {
+                    year: 2021,
+                    month: 7,
+                    day: 6,
+                    hour: 18,
+                    minute: 14,
+                    second: 47,
+                    millisecond: 123,
+                    microsecond: 456,
+                    nanosecond: 789,
+                },
+                new Temporal.PlainDateTime(2021, 7, 6, 18, 14, 47, 123, 456, 789),
+            ],
+        ];
+        for (const [arg, expected] of values) {
+            expect(plainDateTime.with(arg).equals(expected)).toBeTrue();
+        }
+
+        // Supplying the same values doesn't change the date/time, but still creates a new object
+        const plainDateTimeLike = {
+            year: plainDateTime.year,
+            month: plainDateTime.month,
+            day: plainDateTime.day,
+            hour: plainDateTime.hour,
+            minute: plainDateTime.minute,
+            second: plainDateTime.second,
+            millisecond: plainDateTime.millisecond,
+            microsecond: plainDateTime.microsecond,
+            nanosecond: plainDateTime.nanosecond,
+        };
+        expect(plainDateTime.with(plainDateTimeLike)).not.toBe(plainDateTime);
+        expect(plainDateTime.with(plainDateTimeLike).equals(plainDateTime)).toBeTrue();
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainDateTime object", () => {
+        expect(() => {
+            Temporal.PlainDateTime.prototype.with.call("foo");
+        }).toThrowWithMessage(TypeError, "Not an object of type Temporal.PlainDateTime");
+    });
+
+    test("argument must be an object", () => {
+        expect(() => {
+            new Temporal.PlainDateTime(1970, 1, 1).with("foo");
+        }).toThrowWithMessage(TypeError, "foo is not an object");
+        expect(() => {
+            new Temporal.PlainDateTime(1970, 1, 1).with(42);
+        }).toThrowWithMessage(TypeError, "42 is not an object");
+    });
+
+    test("argument must have one of 'day', 'hour', 'microsecond', 'millisecond', 'minute', 'month', 'monthCode', 'nanosecond', 'second', 'year'", () => {
+        expect(() => {
+            new Temporal.PlainDateTime(1970, 1, 1).with({});
+        }).toThrowWithMessage(
+            TypeError,
+            "Object must have at least one of the following properties: day, hour, microsecond, millisecond, minute, month, monthCode, nanosecond, second, year"
+        );
+    });
+
+    test("argument must not have 'calendar' or 'timeZone'", () => {
+        expect(() => {
+            new Temporal.PlainDateTime(1970, 1, 1).with({ calendar: {} });
+        }).toThrowWithMessage(TypeError, "Object must not have a defined calendar property");
+        expect(() => {
+            new Temporal.PlainDateTime(1970, 1, 1).with({ timeZone: {} });
+        }).toThrowWithMessage(TypeError, "Object must not have a defined timeZone property");
+    });
+});