The 27-year-old former Red Bull Salzburg left back has sealed a free transfer to Bundesliga side FC Koln.
Mensah joined Auxerre following his departure from Salzburg in 2022, having spent much of his time at the club out on loan, at the likes of Sturm Graz, Zulte Waregem, Vitoria de Guimaraes and Bordeaux.
It was with Les Ajaïstes where the Black Stars international established himself and he went on to feature 114 times for the club and was an important part of their 2024 Ligue 2 title triumph.
"A great adventure comes to an end between AJA and Gideon Mensah," the club wrote.
"Champion of Ligue 2 in 2024, the Ghanaian international contributed significantly to AJA's return to the top flight before playing a major role in the club's two consecutive survivals in Ligue 1.
“Combative, generous, and always impeccable on the pitch, Gide will leave a wonderful legacy at AJA and with all its supporters.”
