Roche, who will turn 33 tomorrow, has made 179 appearances in a nine-year spell with Exiles.
He joined Irish from Saracens in 2003 and helped shape a formidable lineout with fellow stalwarts Bob Casey and Nick Kennedy
Irish head coach Toby Booth paid tribute to Roche, saying: "Kieran has been one of London Irish's greatest servants. A true professional and we thank him for his outstanding dedication and commitment to the club.
"We would like to wish him and his family all the very best for the future. We know that he will be successful in his future career and we wish him luck. "
Roche said: "I would like to thank everyone who has played a part in my rugby career, from my school days onwards, including the players, coaches and support staff that I have worked alongside both at Saracens and London Irish.
"I would also like to thank the supporters of both clubs; particularly those at London Irish who have made me feel a real part of such a great club for the last 10 years. A special thank you goes to my family who have given so much in support of my rugby.
"As with all players moving on from the game I will leave having made many lifelong friends and with many great memories of my time playing rugby.
"I'm looking forward to taking to the field one last time for London Irish at Madejski Stadium this weekend alongside some of those friends and hoping for a victorious send off for everyone who is moving on."