During his early career, he continued his studies at the French National Institute of Applied Sciences in Rennes, and graduated in 2007 in mechanical and automated engineering.

Despite splitting his time between studying and cycling, Roy still finished 4th in the Tour de Picardie and won the young rider competition in 2006.

Roy gained his first professional victory on 12 March 2009, when he won stage 5 of Paris–Nice, beating his breakaway companion Thomas Voeckler in a sprint.

The following year he won the Tro Bro Leon, performed well in the La Flèche Wallonne and finished third in the prologue of the Tour de Romandie.

Roy came agonisingly close to winning stage 13, finishing third after being caught with 2.5 km to go, by Thor Hushovd and David Moncoutié, after a challenging pursuit in the final kilometres.