Hamilton West—Ancaster—Dundas (French: Hamilton-Ouest—Ancaster—Dundas) is a federal electoral district in Ontario. It encompasses a portion of Ontario previously included in the electoral districts of Ancaster—Dundas—Flamborough—Westdale, Hamilton Centre and Hamilton Mountain. Hamilton West—Ancaster—Dundas was created by the 2012 federal electoral boundaries redistribution and was legally defined in the 2013 representation order. It came into effect upon the call of the 42nd Canadian federal election, on October 19, 2015.