Ian McGeechan has quit his post as director of rugby with Scotland to take up a similar post with Wasps.
McGeechan has plenty of experience of English rugby
Scot McGeechan, 58, will take over from Warren Gatland when he returns from assistant coach duties with the Lions.
"While I'm delighted to accept the new post this has been a difficult decision for me," said the former Lions, Scotland and Northampton coach.
"Everyone in Scotland may rest assured that my passion for the game here remains undiluted."
McGeechan, who has signed a two-year deal with the London side, led Scotland to the Grand Slam in 1990 and was in charge at Northampton for six years up to 1999.
He also coached the Lions on their 1989, 1993 and 1997 tours.
McGeechan will head a coaching team which also includes Shaun Edwards and another new appointment, technical analyst Leon Holden, a replacement for Tony Hanks, who is also returning to New Zealand.
McGeechan said: "I have a lot of respect for what Wasps represent and also for the club and the players.
"This is a top club who are ambitious and have already achieved a lot in the game.
1946: Born 30 October, Leeds
1972: Makes Scotland debut
1974: Lions tour to South Africa and Rhodesia
1977: Lions tour to New Zealand and Fiji
1988: Promoted to Scotland coach from assistant
1989: Lions coach for Australia tour - won series 2-1
1990: Guides Scotland to Grand Slam
1993: Lions coach in NZ - lost series 2-1
1994: Appointed Northampton director of rugby
1997: Lions coach in South Africa - won series 2-1
1999: Assumes Scotland coach role from Jim Telfer
2002: Replaces Telfer as SRU director of rugby
2005: Resigns from Scotland post to join Wasps
"It's a huge challenge to follow on from the success and outstanding achievements of Warren Gatland.
"I'm facing a learning curve, in the need to understand the club in order to do it justice, but once I've done that I can start to look at ways of taking the club further forwards."
Wasps chief executive David Davies said: "For Wasps, as a club, to get one of the world's foremost coaches is a mark of the club's standing.
"I do believe that we will have a coaching team whose strength matches that of the squad we currently have at Wasps.
"This arrangement gives the clear indication to our supporters all over the world that we intend to stay at the forefront of English and European club rugby.
"We do not intend to change the recruitment policy; we intend to continue recruiting and developing predominantly English players.
"In making this appointment we have invested a lot of thought - it's taken nearly four months to get to this point and it¿s a decision that we haven't taken lightly."
McGeechan had been Scotland's director of rugby since stepping down as coach after the 2003 World Cup.
He handed control to Matt Williams but the Australian now finds his own job on the line after winning just three of 17 Test matches, including just one in 10 six Nations games.
Scottish rugby boss Fred McLeod said: "For many of those in Scottish Rugby who recognise what he has achieved, this is extremely regrettable news.
"Geech's contribution on the field as a distinguished player, then as a coach and in his post as director of rugby has been immense.
"He will remain in post until he departs on the Lions tour on 13 May and will be fully involved in all aspects of the union's business in the meantime."