London Irish RFC is a professional English rugby union club, with an Irish identity. It was originally based in Sunbury, Middlesex, where the senior squad train, youth teams and senior academy play home games, and the club maintain their administrative offices, at Hazelwood Drive. It has competed in the Premiership, the top division of English rugby union, every season since its inception in 1996–97, apart from the 2016–17 and 2018–19 seasons, in which the club competed in the RFU Championship, winning the league and promotion both times. The club also competed in the Anglo-Welsh Cup, until the tournament's demise in 2018, and has participated in both the European Champions Cup and European Challenge Cup. While playing in the Championship, in 2016–17 and 2018–19, Irish also played in the British and Irish Cup and its successor the RFU Championship Cup respectively. The club played its home games at the Madejski Stadium in Reading, Berkshire for 20 years. However, for the 2020–21 season they moved to Brentford Community Stadium in Brentford, west London.

London Irish won its first major trophy in 2002, claiming the Powergen Cup (the competition that is now the Premiership Rugby Cup). Irish also reached the final of the 2009 English Premiership, narrowly losing 10–9 to Leicester Tigers at Twickenham Stadium. In the 2007–08 season the team came close to a place in the Heineken Cup Final, losing out to Stade Toulousain 15–21 in a tense semi-final encounter at Twickenham Stadium.The club's mascot is an Irish Wolfhound character called Digger.