The 27-year-old forward moves to Ligue 1 following a four-year spell at Crystal Palace.
Édouard scored 21 goals in 105 appearances for the club – a figure which includes his memorable brace in his first game against Tottenham Hotspur, when he became the fastest debutant goalscorer in Premier League history.
The striker spent last season on loan in the Premier League with Leicester City, but now returns to France in a permanent move.
Everyone at Crystal Palace wishes Odsonne the best of luck with the next chapter of his career.