The 56-time Ireland international was part of the Leinster squads that triumphed in the 2009, 2011 and 2012 finals, and also helped Irish province claim the Challenge Cup in 2013.

O’Brien, a former British & Irish Lion, featured 54 times in European competitions, scoring 12 tries. He joined London Irish in 2019 and has since turned out for the Gallagher Premiership side in the Challenge Cup.

The 35-year-old said in a statement: “After much deliberation and consultation with my family and friends, I can confirm that I have decided to retire from playing professional rugby at the end of the season.

“I’ve had an incredible career and am thankful for every second of my time at Leinster, Ireland, London Irish and the British and Irish Lions.”

Speaking to leinsterrugby.ie, Leinster head coach Leo Cullen added: “Seán will be remembered as one of the very special Leinster players, particularly his performances in helping Leinster win the Heineken Cup in 2011 and 2012.

“He was a fearless competitor and he gave incredible confidence to those around him.”

London Irish forward Seán O’Brien, who lifted the Heineken Cup three times with Leinster Rugby and was named EPCR European Player of the Year in 2011, has announced that he will retire at the end of the season.