The Ivory Coast international, who can play as a striker as well as a winger, has thanked his coach Christophe Galtier, his coaching staff and his teammates.
“I had the chance to play for ASSE and had good times with my coach Galtier, his staff and my teammates,” Gradel wrote on Twitter. "I always gave everything for ASSE, but everything has an end."
Jais eu la chance de jouer pour l asse et jais passée des bons moments avec le coach galtier et tout son staff et mes coéquipiers— Maxi Alain Gradel (@maxigr04del) August 3, 2015
Jais toujours tout donner pour l asse chaque chose à une fin je quite les verts car c'était prévus— Maxi Alain Gradel (@maxigr04del) August 3, 2015
According to Sky Sports, the 27-year-old is set to join newly-promoted Premier League outfit Bournemouth.
It has been reported that the former Leicester and Leeds man has undergone a medical and will complete his move to the Cherries by tomorrow.
The attacker scored 17 goals and created 46 chances in 31 Ligue 1 appearances for Saint-Etienne last season.
Gradel had a pass accuracy of 72% and a shot accuracy of 49%, and won 16 headers, 45 dribbles and 47 tackles.
The Ivorian did not fare well at Leicester, but he made himself popular among the Leeds fans after scoring 25 goals in 77 league games for the West Yorkshire outfit.