At the 2012 World Championships in Heerenveen , Mulder wins the silver medal over 2 × 500 m. In 2013, Mulder won the world sprint four-way championship in Salt Lake City . He set a new point record. At the 2014 Winter Olympics in Sochi , he won the 2 × 500 m title. Jan Smeekens and Mulder's twin brother Ronald followed on the seats . The Mulders are only the second pair of twins at the Winter Olympics (after Phil and Steve Mahre 1984) to win medals in a competition at the same time.
Mulder's inline speed skating focuses on the sprint courses and the relay. He has won several medals at world and European championships. At the 2012 World Cup , he won his first world title over 500 m.