Rennes On 3 March 2020, Assignon signed his first professional contract with
Rennes. During the second half of the 2020–21 season, he was loaned to third-tier
Bastia, where he helped the club win the
Championnat National, contributing one goal in thirteen appearances. On 8 September 2022, he scored his first professional goal for Rennes, a last-minute winner in a 2–1
UEFA Europa League victory over
AEK Larnaca. Sports newspaper ''
L'Équipe'' described his goal as "
Zlatan-esque".
Burnley (loan) On 1 February 2024, Assignon was loaned out to English side
Burnley until the end of the season with an option to buy. On 30 March 2024, Assignon gave away a penalty and got a
red card after receiving his second booking for a foul on
Mykhailo Mudryk, with the game against
Chelsea ending in a 2-2 draw. After his second yellow card,
Vincent Kompany was also sent off for protesting against the referee
Darren England over awarding the home side the penalty. On 20 April 2024 he became just the second Burnley defender to both score and assist in a single Premier League game, in a 4-1 away win at
Sheffield United. On 21 May 2024, Burnley said it was moving to make the loan permanent.
VfB Stuttgart On 6 June 2025, Assignon signed a four-year contract with
VfB Stuttgart in Germany. ==Personal life==