Lorenz Assignon joined SRFC's academy in 2015 and made his professional debut six years later, aged 21, when he played in the European Cup and travelled to Rosenborg in the UEFA Conference League qualifiers on 26 August 2021 (1-3 win).

A season earlier, on loan at SC Bastia, the right-back played 13 league games in the third division. The player who learnt in the footsteps of Hamari Traoré played a total of 67 games for his former club (3 goals, 6 assists). During the second half of the 2023/2024 season, Lorenz left for the Premier League, where he made 15 appearances for Burnley FC, scoring 1 goal and providing 2 assists.

Lorenz Assignon, a player on whom the club is pinning a lot of hopes, is also « delighted to be staying at Rennes, where it all began. You hear a lot of noise during a transfer window, but the reality is that I'm staying with the Stade Rennais family. I'm growing with the club, there's a new project, new players, and I'm very happy to be part of it. I've come back stronger and more ambitious after six months in the Premier League, and I've learnt a lot. The aim is to get back to Europe as quickly as possible.