The 29-year-old French striker served up some unforgettable moments during an action-packed two-season stay with the Billy Goats, from his comical goal celebrations to his kung-fu strike against champions Bayern Munich.
Watch: Anthony Modeste's Goal of the Season contender
A statement on the Billy Goats' official website read: "Cologne thanks Tony for his efforts and wishes him all the best for the future."
Modeste was already well known to Bundesliga audiences when he made the switch to the RheinEnergieStadion in summer 2015, having scored 23 goals in 62 appearances for former employers Hoffenheim between 2013 and 2015, but it was in Cologne where he truly came of age.
After helping himself to 15 Bundesliga goals in his debut campaign for the club, the ex-Nice, Angers, Bordeaux, Blackburn Rovers and Bastia forward rattled off 25 strikes in 2016/17.
Although he finished six goals short of Borussia Dortmund's Pierre-Emerick Aubameyang and five adrift of Bayern's Robert Lewandowski at the top of the scoring charts, Modeste's career-best single-season haul ensured Cologne's return to major continental competition for the first time in 25 years.
Watch: Anthony Modeste on a season to savour with Cologne
Confirmation of Modeste's departure comes soon after the German city of Frankfurt hosted the first ever Chinese-German Football Summit - an exchange between leading representatives of both countries' football associations as well as the Chinese Super League (CSL) and Bundesliga clubs.
Watch: Around 200 participants attended the first Chinese-German Football Summit