"I am grateful for having had the privilege to serve the club for so many memorable years."
In 1996, Wenger went into Arsenal - then based at Highbury - as an unknown 46-year-old.
But in his first full season in charge, he led the side to the league and FA Cup double. Two more Premier League titles and six more FA Cups have followed.
His championship winning team of 2003-04 attained legendary status and were dubbed 'the Invincibles' for remaining unbeaten throughout the entire season.
But the superlatives of that campaign have never been revisited. Chelsea, Manchester City and especially Manchester United have since gobbled up the titles.
Those failures to win the main domestic prize have been mitigated by qualification for the Uefa Champions League. However the inability to qualify for the 2017/18 tournament and abject league form this season have increased the pressure on the Frenchman.
A path to the 2018/19 Champions League remains via victory in the Europa League. Atletico Madrid lie in Arsenal's way in the semi-final.
"I urge our fans to stand behind the team to finish on a high," added Wenger. "To all the Arsenal lovers take care of the values of the club. My love and support for ever."
Arsenal's majority shareholder Stan Kroenke paid tribute to Wenger's contribution hailing him as a man of unparallelled class.
"Everyone who loves Arsenal and everyone who loves football owes him a debt of gratitude," said Kroenke, who took a controlling stake in the club in 2011.
"One of the main reasons we got involved with Arsenal was because of what Arsene has brought to the club on and off the pitch. His longevity and consistency over such a sustained period at the highest level of the game will never be matched."
Arsenal added that a successor to Wenger will be found as soon as possible.