After spending time with the youth team and reserve team, Grandsir signed with the Troyes senior team in 2016.[citation needed]
Garnering attention from other clubs after several impressive seasons, he moved to Monaco for €5.250m in 2018.[citation needed] Grandsir went on loan from Monaco to Strasbourg in January 2019 followed by another loan to Brest for the 2019–20 season.[2]
On 11 March 2021, Grandsir signed with Major League Soccer club LA Galaxy.[3] On 23 January 2023, Grandsir returned to his native France to join Ligue 2 leaders Le Havre on a contract until the end of the season.[4][5]
International career
Born in France, Grandsir holds French and Senegalese nationalities.[6][7] He represented France at the youth international level.