Markham—Stouffville is a federal electoral district in Ontario, Canada. It encompasses a portion of Ontario previously included in the electoral districts of Markham—Unionville and Oak Ridges—Markham. Markham—Stouffville was created by the 2012 federal electoral boundaries redistribution and was legally defined in the 2013 representation order. It came into effect upon the dropping of the writs for the 2015 federal election. Helena Jaczek has represented the riding since the 2019 federal election.