Born in Mâcon, Rongier joined Nantes' youth academy in 2001. He made his Ligue 1 debut for the club on 18 October 2014 against Reims in a 1–1 draw, coming off the bench to replace Lucas Déaux in the 78th minute mark.[3] He was appointed club captain ahead of the 2018–19 season.
Marseille
On 3 September 2019, Rongier joined Olympique de Marseille on a five-year contract for a €13 million transfer fee.[4] The transfer was completed outside the transfer window dates thanks to a "joker" transfer exemption created by the Ligue de Football Professionnel.[5]