Wasps have named Dai Young as their new director of rugby, on a four-year deal.
Young teams up with Wales defence coach Shaun Edwards and ex-Cardiff fly-half Nicky Robinson, who has joined Wasps.
"This is an enormous opportunity. I loved my time at Cardiff but I'm looking forward to a new experience in a new environment," said Young.
"There are hugely talented players here and the chance of helping a great club to challenge for success again was too good to turn down."
The move leaves Young's former team Cardiff Blues seeking a replacement for a role in which ex-Wasps boss Tony Hanks has expressed an interest.
There has also been speculation that the Blues will put Young's ex-assistants Gareth Baber and Justin Burnell in charge.
Young resigned from his Blues role with a year left on his contract to take up the Premiership club's offer.
Wasps chief executive Chris Thomas hopes he will be able to spark a revival in the two-time Heineken Cup and six-time Premiership champions' fortunes.
"We believe Dai is exactly the right person to take the club forward," Thomas said.
"Dai brings a wealth of experience to the club and this is an appointment for the long term.
"We remain an ambitious club and want to be competing at the highest level. Dai is the person to help us achieve these ambitions."
Young became the first Welsh regional boss to win European silverware when they beat Toulon 28-21 in the 2009 Amlin Challenge Cup final.
The 43-year-old guided the Blues to a Heineken Cup semi-final in 2009, where they were beaten in a penalty shoot-out by Leicester, and took them to Anglo-Welsh Cup success in the same year.
The former Wales and British and Irish Lions tight-head prop began his career at Swansea, and moved to Cardiff RFC before switching to rugby league with Leeds in 1990.
In 1991 Young moved to Salford, also playing for the Wales tugby league side before returning to union in 1996 and resurrecting his career with the Blue and Blacks, Wales and the Lions.
Earlier this year he was in charge of the Barbarians for victories over an England XV and Wales.
Wasps had been without a full-time director of rugby since Hanks' departure in February.