Kanervo broke 50 seconds in the 400 m hurdles for the first time on 11 April 2015 in Greenville, North Carolina, running 49.78. He suffered from a persistent groin injury through the 2015 collegiate season, but stayed in good form; he qualified for his first NCAA championship final, placing sixth in 50.20. At the 2015 European U23 Championships in Tallinn Kanervo improved his personal best to 49.66, winning silver behind Patryk Dobek of Poland; he was Finland's only medalist.