In his 2nd year as professional, in 2008, he showed progression by winning the hardest stage in the Tour of California, where Gesink rode away on the final climb, with only Levi Leipheimer holding his wheel. They stayed ahead on the final 35 kilometers of downhill and flat and Leipheimer did not contest Gesink in the sprint. Gesink won the young riders jersey again and finished 9th in the general classification. In the Paris-Nice he finished second in the stage up to Mont Serein, five kilometers before the top of Mont Ventoux, where he was outsprinted by Cadel Evans. He then lost the leader's jersey in the penultimate stage to Cannes, when he got isolated on the Col du Tanneron which, together with Gesink's overly careful descent, allowed Davide Rebellin to take the leader's jersey. He finished fourth in the overall classification, 51 seconds behind Rebellin, which won Gesink the youth classification. He also finished twelfth in the Tour of the Basque Country and completed a successful Ardennes classics by finishing fourth in La Flèche Wallonne. In September, he then finished seventh in his first Grand Tour, the Vuelta a España.