Tadhg Beirne has signed a contract with the IRFU, which will keep him in the country until 2025.
The 29-year-old Beirne described signing the deal - his first ever central contract from the IRFU - as "an easy decision."
The Munster and Ireland flanker has established himself as a front-rank international player since returning from Wales in 2018, earning Lions recognition in 2021.
Beirne orginally came through the Leinster academy but was released by the province in 2016. That summer, he signed for Welsh outfit Scarlets.
He shone for Scarlets, then coached by Wayne Pivac, as they won an unlikely Pro12 title in 2016-17, dispatching Munster in the decider in the Aviva Stadium.
Beirne turned down the offer a new contract with Scarlets to return to Munster, motivated by his desire to play for Ireland.
Beirne said: "I have made some tough decisions in my career but this was an easy one. I am grateful to everyone who has supported me on this journey - my family, my partner and the different coaches along the way who helped me become a better player.
"Representing Munster, Ireland and the Lions over the past few seasons has been fantastic and I am looking forward to contributing in red and green in the years to come."
David Nucifora, IRFU Performance Director, has said Beirne has earned the deal: "Tadhg's journey to a green jersey has not been a straight line but he backed himself and proved his quality.
"Since his return to Ireland in 2018 he has continued to improve his game and illustrate his worth to both Munster and Irish rugby with the consistency and quality of his performances."