Here, we take a look back at some of the highs and lows of the Frenchman's reign.
The unheralded former Monaco and Nagoya Grampus Eight coach was appointed Arsenal manager in September 1996 and won his first game in charge 2-0 at Blackburn, with two goals from Ian Wright as the Gunners went on to finish in third place in the Premier League and secured a place in the UEFA Cup.
Under Wenger's guidance, Arsenal also won the 1997/1998 Premier League title and secured the Double with victory over Newcastle in the FA Cup final.
Arsenal had to make do with runners-up spot in the 1998/1999 league race to Manchester United, though, and the Red Devils also knocked them out of the FA Cup semi-finals after a replay with a wonder goal from Ryan Giggs.
It was second best again for Wenger's men in 2000 after they finished behind United and although they reached the final of the UEFA Cup, Arsenal suffered an agonising penalty shoot-out defeat to Galatasaray in Copenhagen.
Wenger received a 12-match touchline ban after being found guilty by the Football Association of "threatening behaviour and physical intimidation" to fourth official, Paul Taylor, after defeat on the opening day of the 2000/2001 season at Sunderland but the decision was later overturned by an appeal board.
More heartache came for the Gunners as they were beaten to the Premier League title by United once more, and then they somehow lost the 2001 FA Cup final against Liverpool due to a late brace from Michael Owen despite dominating the match in Cardiff.
The 2001/02 campaign saw Wenger's Arsenal rejuvenated as the likes of Sol Campbell, Giovanni van Bronckhorst, Fredrik Ljungberg, Thierry Henry and Robert Pires drove the side on to a second Double, securing the league title with victory over United at Old Trafford having beaten Chelsea in the FA Cup final
Arsenal were runners-up to United again in May 2003, but retained the FA Cup by beating Southampton 1-0 at the Millennium Stadium,
In June 2003, Wenger received an honorary OBE in Queen's birthday honours list.
Wenger's crowning glory were his "Invincibles" who were champions after having gone through the entire 2003/2004 season unbeaten.
Arsenal's 49-match unbeaten league run was finally ended with a 2-0 defeat in a feisty encounter with United at Old Trafford in October 2004. The match became known as the 'battle of the buffet' following a heated exchange with Sir Alex Ferguson in the tunnel after the match.
Arsenal then won the 2005 FA Cup with a penalty shoot-out win over United.
Arsenal suffered a defeat in the 2006 Champions League final by Barcelona in Paris, where goalkeeper Jens Lehmann was sent off early in the first half.
The north London club then moved to the impressive 60,000-seater Emirates Stadium for the start of the 2006/2007 season, with Wenger having overseen the club's transition from Highbury.
Arsenal next reached the final of the Carling Cup against Chelsea. Despite taking the lead through Theo Walcott's first goal for the Gunners, Didier Drogba struck twice to secure victory for the Blues in Cardiff.
Wenger's long-time ally David Dein then left his role as Arsenal vice-chairman in April 2007, which was followed by the sale of Thierry Henry, Arsenal's club-record scorer, to Barcelona in the summer.
In February 2008, Arsenal striker Eduardo suffered an horrific injury in a tackle from Martin Taylor at Birmingham, which led to Wenger calling for the defender to be "banned for life" in the immediate aftermath. Arsenal were eventually overtaken by Manchester United and Chelsea as they finish third.
Wenger ended speculation about his future by penning a new three-year deal in August 2010.
Arsenal suffered a shock defeat to Birmingham in the 2011 Carling Cup final at Wembley after a mix-up between goalkeeper Wojciech Szczesny and defender Laurent Koscielny gifted Blues striker Obafemi Martins a late winner at Wembley. Arsenal saw their title challenge fade and also went of the FA Cup to United.
Goals from Robin van Persie and Andrei Arshavin give Arsenal a famous 2-1 win over Barcelona at the Emirates Stadium in February 2011. However, Lionel Messi inspired the Spaniards to a 3-1 victory in the return leg, where Van Persie was sent off and Nicklas Bendtner missed a late chance to send Arsenal through.
Arsenal reluctantly sold club captain Cesc Fabregas back to his boyhood club Barcelona for some £30million, while Samir Nasri left for Manchester City in another big-money departure to leave Wenger's plans for the 2011/2012 campaign in tatters.
The Gunners were thrashed 8-2 at Manchester United and ended August 2011 just above the relegation zone, with defeat away to Tottenham in October making it the worst start to a season in 58 years.
In February 2012, Arsenal were thrashed 4-0 by AC Milan in the first leg of their Champions League last 16 tie, a result Wenger labelled "our worst night in Europe". Arsenal won the second leg at home 3-0, but the damage had already been done.
After three successive draws, the Gunners beat West Brom 3-2 on the final day of the season to snatch third place in the table ahead of Spurs and so qualify for the Champions League once again, with captain Van Persie plundering 37 goals.
Van Persie, who failed to agree a new Arsenal contract, was sold to Manchester United in August 2012 for £24million.
Arsenal were beaten 2-0 at home by Swansea in December 2012 to sit 10th in the Premier League.
The Gunners were beaten by League One Bradford in the quarter-finals of the League Cup, then crashed out at home to Championship side Blackburn in the 2013 FA Cup before being outclassed 3-1 at home by Bayern Munich in the Champions League.
Arsenal produced a brilliant performance to win the second leg of their last 16 clash 2-0 in the Allianz Arena, but exited the competition on away goals.
Spurs looked to have taken a grip on the race for a top-four finish when they beat Arsenal 2-0 at White Hart Lane - a result which then Spurs manager Andre Villas-Boas declared would send the Gunners into a "negative spiral".
Boosted by their victory over Bayern, Arsenal went on to win eight from the final 10 Premier League games, beating Newcastle 1-0 on the last day, to overhaul Spurs once again and finish in the top four.
Arsenal lost the opening game of the new Premier League season 3-1 at home to Aston Villa.
The club transfer record was shattered by the deadline day £42.5m signing of German playmaker Mesut Ozil from Real Madrid, as Arsenal booked their place in the group stages of the Champions League and returned to form to move clear at the top of the Premier League.
After a stuttering run of league form saw them drop to third, Arsenal beat Everton to reach the FA Cup semi-finals at Wembley - where they will face Wigan for the chance to meet either Sheffield United or Hull as Wenger sets his sights on a first trophy since 2005.