diff --git a/v2/au/au_holidays.go b/v2/au/au_holidays.go
index c4f9554..87233b0 100644
--- a/v2/au/au_holidays.go
+++ b/v2/au/au_holidays.go
@@ -177,6 +177,16 @@ var (
 		Weekday: time.Monday,
 		Offset:  -1,
 		Func:    cal.CalcWeekdayOffset,
+		EndYear: 2021,
+	}
+
+	// KingsBirthdayWa represents King's Birthday in WA previously known as the Queen’s Birthday;
+	// there is no firm rule to determine this date, though it is usually the last Monday of September
+	KingsBirthdayWa = &cal.Holiday{
+		Name:      "King's Birthday",
+		Type:      cal.ObservancePublic,
+		Func:      calcKingsBirthdayWa,
+		StartYear: 2022,
 	}
 
 	// FridayBeforeAflFinal represents the Friday before the AFL Grand Final;
@@ -370,6 +380,7 @@ var (
 		AnzacDayActWa,
 		WesternAustraliaDay,
 		QueensBirthdayWa,
+		KingsBirthdayWa,
 		MourningDay2022,
 		ChristmasDay,
 		BoxingDay,
@@ -389,3 +400,12 @@ func calcFridayBeforeAflFinal(_ *cal.Holiday, year int) time.Time {
 		return aflFinalDay.AddDate(0, 0, -1)
 	}
 }
+
+func calcKingsBirthdayWa(_ *cal.Holiday, year int) time.Time {
+	switch year {
+	case 2024:
+		return time.Date(year, time.September, 23, 0, 0, 0, 0, cal.DefaultLoc)
+	default:
+		return cal.DayStart(cal.WeekdayN(year, time.September, time.Monday, -1))
+	}
+}
diff --git a/v2/au/au_holidays_test.go b/v2/au/au_holidays_test.go
index 443e2ed..e2c6c8a 100644
--- a/v2/au/au_holidays_test.go
+++ b/v2/au/au_holidays_test.go
@@ -198,7 +198,9 @@ func TestHolidays(t *testing.T) {
 		{QueensBirthdayWa, 2019, d(2019, 9, 30), d(2019, 9, 30)},
 		{QueensBirthdayWa, 2020, d(2020, 9, 28), d(2020, 9, 28)},
 		{QueensBirthdayWa, 2021, d(2021, 9, 27), d(2021, 9, 27)},
-		{QueensBirthdayWa, 2022, d(2022, 9, 26), d(2022, 9, 26)},
+
+		{KingsBirthdayWa, 2022, d(2022, 9, 26), d(2022, 9, 26)},
+		{KingsBirthdayWa, 2024, d(2024, 9, 23), d(2024, 9, 23)},
 
 		{FridayBeforeAflFinal, 2015, d(2015, 10, 2), d(2015, 10, 2)},
 		{FridayBeforeAflFinal, 2016, d(2016, 9, 30), d(2016, 9, 30)},