Carlqvist won the F.I.M. 250cc Motocross World Championship in 1979 as a member of the Husqvarna factory racing team. In 1980, he switched to Yamaha to contest the 500cc motocross world championship. He finished 3rd in 1981 and 1982. In 1983, he battled against Honda teammates André Malherbe and Graham Noyce to claim the 500cc world championship, on a Yamaha. In 1984, an injury stopped Carlqvist from contesting the title again. He raced for Yamaha until end of 1986.