Former England assistant coach Andy Farrell will become Ireland defence coach after this year's Six Nations.
Farrell, 40, joins Joe Schmidt's Ireland set-up after losing his England role when head coach Stuart Lancaster left after the World Cup.
The former rugby league star was defence coach for the victorious British and Irish Lions in 2013.
"To have this opportunity to work with a very talented management and playing group really excites me," said Farrell.
"With a wealth of top-class, experienced senior players and a fantastic crop of youngsters pushing hard, the future is very positive for Irish rugby and I can't wait to get started."
O'Driscoll backs Farrell appointment
Farrell's Ireland contract will begin before the tour to South Africa in June and will run until the completion of the 2019 World Cup in Japan.
Schmidt welcomed Farrell's appointment, which fills the gap left by the departure of Les Kiss to Ulster.
"The quality of his delivery and breadth of his experience, as well as the positive impact he had when coaching a number of our senior players during the 2013 Lions tour, will add real value for us," said Schmidt.
Farrell spent four years as an England assistant coach, and was part of Warren Gatland's coaching team during the 2013 Lions victory.
He lost his job in the England set-up in December as new coach Eddie Jones opted to not retain him, along with Lancaster's other assistant coaches Graham Rowntree and Mike Catt, following the team's dismal World Cup campaign.
Farrell had an outstanding rugby league career, making 370 appearances for Wigan and playing for both England and Great Britain.
After switching codes to join Saracens, he won eight England caps, including three appearances during the 2007 World Cup.
His son Owen has won 35 England caps and was part of the country's World Cup squad last autumn.