Tour de Ski
Sundby and compatriot Therese Johaug became the first Norwegians to win the Tour de Ski when they won the men's and women' competitions in the 2013–14 edition of the race. Sundby subsequently won the overall and distance competitions in the 2013–14 FIS Cross-Country World Cup. He also won the 2016 Tour de Ski. In addition to his Tour de Ski victories, Sundby won the inaugural Ski Tour Canada, despite starting behind Sergey Ustiugov and Petter Northug on the final stage.