The 2011–12 season was Arsenal's 20th season in the Premier League, and also marked the club's 125th anniversary. Arsenal's attempts to win silverware all proved fruitless. In the Premier League, Arsenal struggled to recover from a poor start to the season. Though they did finish the season in the final qualification berth for the next season's UEFA Champions League. Arsenal's UEFA Champions League campaign once again proved unsuccessful, falling at the first hurdle in the knockout stage, with a 4–0 defeat at Milan ultimately proving fatal. Exiting the FA Cup at the fifth round stage at the hands of Sunderland, and the League Cup in the quarter-finals against Manchester City, the two domestic cups were also out of Arsenal's reach.

Arsenal finished the season in third place after winning their last league match 3–2 against West Bromwich Albion on 13 May 2012. It was the first season since the invicibles in 2003–04 which Arsenal finished the top London club in the league, or in which Arsenal finished ahead of Chelsea.

Arsenal's pre-season transfer activity was once again dominated by media speculation regarding the future of club captain Cesc Fàbregas, whose return to boyhood club Barcelona was widely expected, although not officially confirmed until the middle of August when an initial fee in the region of £30 million was agreed between the two clubs. Prior to this, the Gunners' first signing came in the form of young English-Finnish right-back Carl Jenkinson from Charlton Athletic on 8 June for an initial fee of around £1 million, while the first major signing did not come until 11 July with the signing of Gervinho from French champions Lille for more than £10 million. The only notable exits in July came in goalkeeper Jens Lehmann, who retired for the second time, having come out of his first retirement in March to solve an injury crisis that left Arsenal with just one match-fit goalkeeper, while Gaël Clichy joined Manchester City. It was August before the club's transfer activity increased, with promising young striker Alex Oxlade-Chamberlain joining from Southampton for a reported £12 million, before the departures of Fàbregas to Barcelona, the long-serving Emmanuel Eboué to Turkish side Galatasaray, and Samir Nasri to Manchester City for a fee of £25 million. Left-back Armand Traoré's departure to newly-promoted Queens Park Rangers on the penultimate day of the transfer window completed the departures from the first team, before Arsène Wenger, under increasing criticism for the lack of arrivals so far, went on something of a spending spree in the final 48 hours of the window. South Korea captain Park Chu-young joined from Monaco, before left-back André Santos, centre back Per Mertesacker and midfielder Mikel Arteta all joined in the dying hours of the window, from Fenerbahçe, Werder Bremen and Everton respectively. Yossi Benayoun also joined the club on a season long loan from Chelsea, whilst striker Nicklas Bendtner was loaned to Sunderland for the same period, following fellow first-team members Denílson and Carlos Vela, who had joined São Paulo and Real Sociedad on loan earlier in the window. At the close of the window, Arsenal had spent an estimated £51.2 million, compared to an income of nearly £75 million.

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