At the 2008 Summer Olympics in Beijing, he was a member of the Canadian team that finished sixth in the 4×100 m freestyle event and fifth in the 4×200 m freestyle relay event. Although he qualified third fastest out of sixteen swimmers, one place ahead of Michael Phelps, he did not compete in the semi-finals of the 200 m freestyle. Instead, his coach decided to rest him for the 4×100-metre freestyle, which was held that same day (Hayden set a Canadian record in the opening leg with a time of 47.56). He failed to qualify for the finals in the 100 m freestyle despite being the incumbent World Champion in that event. While Hayden was promoted as the best Canadian swimmer at these games with his world title, only fellow long-distance freestyle Ryan Cochrane managed to medal for the nation in the pool, while the remainder of the swim team failed to make the podium despite a general improvement over their 2004 showing.