Andy Balbirnie, the Ireland captain, will play for Glamorgan in this year's T20 Vitality Blast.
Balbirnie will be available for all 10 group matches, plus the knockout stages if Glamorgan make it that far, after Cricket Ireland approved the move by submitting a No Objection Certificate.
"I'm very pleased to see the deal go ahead - it's a fabulous competition, and having spent a few years in Cardiff during my university days, it's a city I know pretty well," Balbirnie said. ""It's a tournament I've watched a lot and have many friends who have played in it over the years, so I'm looking forward to the opportunity to play with new people and learn from different coaches, as well as to play in a different tournament in different conditions.
"It's not been a great season for playing much cricket, so to be able to go over and play a short, sharp tournament of intense cricket will be enjoyable and a good way to end the summer."
T20 Blast - Full fixture list
Balbirnie struck his sixth ODI century in a 214-run partnership with Paul Stirling to chase down a target of 329 for victory over England earlier this month in the third match of their series, won by England 2-1.
A product of Cardiff MCCU, Balbirnie has has played 70 ODIs for Ireland, scoring 2041 runs with a career-best 145 not out against Afghanistan last year. He has also played 43 T20Is, scoring 945 runs at an average of 25.54 and strike rate of 129.80 with four half-centuries.
Mark Wallace, Glamorgan's director of cricket, said that with David Lloyd suffering a broken foot and Colin Ingram's arrival from South Africa looking unlikely due to Covid-19 travel restrictions, the club wanted to add some batting depth by signing Balbirnie.
"Andrew is a fantastic player with a strong record in the one-day formats and was in great form during the recent series against England," Wallace said. "He is also very used to playing in our conditions and will add a lot of experience and class at the top of the order."
The 2020 Blast season will start on August 27 with the quarter-finals on October 1 and Finals Day on October 3 at Edgbaston.