The 30-year-old joined the Stadium Municipal outfit from Bournemouth last summer in a bid to get regular playing time after making only in 11 English Premier League games in the 2016-17 season.
The former Saint-Etienne player was a consistent fixture for the French outfit this season featuring in 35 games across all competitions, scoring 11 goals.
On Sunday, the attacker - who featured for the entire duration of the game - helped Mickael Debeve’s side retain their status in the top-flight after defeating AC Ajaccio 1-0 in the relegation play-offs final, with Jimmy Durmaz scoring the solitary goal to end his temporarily stay with the side on a good note.
And the forward has taken to the social media to express his gratitude to the president, manager, staff, players as well as supporters of the club as he departs.
“Thank you very much to Toulouse FC, the president, Pascal Depraz, [coach] Michael Debeve, the players, the staff as well as the supporters,” Gradel tweeted.
“Mission accomplished tomorrow will be better,” he concluded.