He rode the Tour de France 12 times, finishing second twice and winning the stage to Alpe d'Huez on two occasions.

The climax of his amateur career was gold in the Olympic road race in Munich in 1972, riding the final 40 km alone.

His career took off in 1975 when he signed for the Dutch team, Frisol, where he got more chances to shine and formed a partnership with José De Cauwer (who worked for Kuiper in races) that lasted until 1980.

1981 saw him win the Tour of Flanders and the Giro di Lombardia while in 1983 he won Paris–Roubaix, his 11th attempt at the hell of the north.

After retirement Kuiper managed the small German pro squad Team Stuttgart between 1989 and 1990.