Born in Dourdan, Île-de-France, Gallopin previously resided in Angerville.

[4] On 13 July 2014 Gallopin escaped in a breakaway on Stage 9 of the Tour de France, gaining almost 8 minutes on the leader Vincenzo Nibali to take the yellow jersey.

He won stage 7 of the 2018 Vuelta a España after attacking inside the last 3 kilometers.

[10] Gallopin announced that he would retire from cycling at the end of the 2023 season following a 16-year professional career.

[11] In February 2020, Rousse announced via an Instagram post that the couple had separated.