Ireland have confirmed Mike Catt's appointment as attack coach after the autumn's World Cup, on a contract to run until 2023.
Current Italy coach Catt will trade the Azzurri for Ireland after the showpiece event in Japan as the final piece of the back-room jigsaw under Andy Farrell.
Catt will be reunited with former England coaching colleague Farrell, who will take over from Joe Schmidt as Ireland head coach after the World Cup.
"Mike brings a wealth of experience to the coaching group and has been operating at the highest level of the international game for some time," said IRFU performance director David Nucifora.
"He was a smart and innovative player, and he brings those attributes and much more besides in his approach to coaching and player development.
"We feel that we have secured a talented practitioner who will add significant value to the group and to the wider Irish system."
Catt's addition will complete Farrell's backroom staff, with John Fogarty coming on board as scrum coach.
Simon Easterby and Richie Murphy will continue as forwards specialist and kicking and skills coach respectively
"I am looking forward to the Rugby World Cup in Japan and seeing the group of players we have here in Italy fulfil their potential and achieve the objectives we have set for ourselves," said Catt.
"Obviously, it is an honour to be given this future opportunity with Ireland but I will focus on that challenge only after I have given my all for Italy and this group of players."
Outgoing boss Schmidt will hope to steer Ireland past the World Cup quarter-finals for the first time in Japan before returning to his native New Zealand.
Former schoolteacher Schmidt will take a break to spend time with family following the World Cup but will command another top-level post as and when he is ready in the future.
Catt's impending arrival will put all of England's World Cup 2015 coaches on Irish shores, with Stuart Lancaster excelling at Leinster and Graham Rowntree joining Munster.
England became the first hosts in World Cup history not to progress past the group stages in 2015, an unwanted record that cost Lancaster and his coaching staff their jobs.
That coaching quartet has quickly restored reputations though, with Lancaster leading Leinster to the 2018 Champions Cup crown and back-to-back PRO14 titles.
Farrell has forged a pivotal part of Schmidt's Ireland set-up as the national side swept to the 2018 Six Nations Grand Slam, before claiming a first win over New Zealand on home soil last November.
Both Farrell and Rowntree helped the Lions secure a drawn Test series against back-to-back world champions New Zealand on the 2017 tour.
Catt has formed part of Conor O'Shea's Italy staff, with the Azzurri working through a laborious task of building infrastructure for future success.
As a player, Catt helped England win the 2003 World Cup, winning 76 caps between 1994 and 2007, while he also won one Lions cap on the victorious South Africa tour in 1997.