At the 2016 Rio Olympics, he won a silver medal alongside Sam Webster and Eddie Dawkins in the team sprint. That year, the team also regained their World title having been relegated from the competition in 2015. Mitchell won a bronze medal at the 2017 UCI Track Cycling World Championships in Hong Kong in the sprint event; the first New Zealander to win a world championship medal in an individual event. He, Dawkins and Webster also retained the men's team sprint title.