London Irish have agreed a deal to sign Ulster fly-half Ian Humphreys, while stalwart Kieran Roche will retire at the end of the season.
Humphreys, 30, still has a year to run on his Ulster contract, but he will now join the Exiles this summer.
The former Leicester Tigers man, who failed to make the Ulster line-up for the Heineken Cup semi-final win over Edinburgh last weekend, has struggled for consistency this season.
Humphreys will be vying with Shane Geraghty - who arrives from Brive at the end of the campaign - for a place in London Irish's starting XV.
Irish rugby director Brian Smith said: "It is fantastic to have Ian on board for the next three seasons. He will bring with him a wealth of experience and leadership qualities.
"He is a constant threat with ball in hand and has a great ability to create space for his outside backs. He also has a fantastic kicking game.
"When I was previously at the club we tried to recruit Ian and Tomas O'Leary, and now we have a pair of Irish half-backs as good as any in Europe.''
Humphreys, 30, and O'Leary are among a clutch of new signings for next term that also includes Catalan Dragons rugby league star Setamaita Sa, Leicester lock George Skivington and Gloucester hooker Scott Lawson.
Humphreys said: "I am very excited to be joining London Irish.
"They play an attractive style of rugby that I am looking forward to being involved in."
Meanwhile, Roche has confirmed he will be retiring from the game after 14 years as a professional.
Roche's final game for the club is this weekend's home clash against Gloucester and he is hoping to finish on a winning note.
"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," he told the club's official website.
"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."