Jonathan made 110 appearances for Leinster between 2006 and 2013 scoring 1,015 points for the province. While at Leinster he won three European Cups, two Pro12 titles and a Challenge Cup.
Sexton made his Ireland debut in the 41-6 victory over Fiji in November 2009. The 29 year old has won 45 caps for Ireland scoring 391 points. His most recent appearance for Ireland was in the 23-17 defeat of Argentina on the 2014 Summer Tour.
Jonathan played in all five games of Ireland's 2014 RBS 6 Nations Championship winning campaign and toured with the 2013 series winning British & Irish Lions squad starting in all three Tests against Australia.
IRFU, CEO, Philip Browne, said, "Jonathan is one the best out-halves in world rugby and the IRFU are delighted that he will be playing his rugby in Ireland. Irish rugby will benefit hugely from having a player of his calibre playing full-time in Ireland."
Commenting on the new contract Jonathan Sexton said, "I am pleased to be re-joining Leinster, the club where I started my professional career. I grew up playing my rugby in Leinster and always wanting to pull on the blue jersey so I am delighted to be able to return to play my club rugby in Ireland."
Guinness PRO12
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