Bill Johnston will move to Ulster this summer from Munster.
The 22-year-old playmaker was given his Munster debut in March 2017 but has made just 12 senior appearances in total, scoring 29 points.
He was a key member of the Ireland side that reached the 2016 Under-20 World Championship final, scoring 11 points in the comeback victory over Wales and another 10 in the historic win over New Zealand.
Johnston said he’s looking forward to the switch: "I’m an ambitious player and this is a great opportunity for me to test myself in an exciting new environment and develop my game under Dan [McFarland] and the other coaches.
"Ulster has a talented young squad that is hungry for success and it’s an organisation that’s clearly moving in the right direction. That’s something I really want to be part of and I can’t wait to make the move to Belfast and get stuck into pre-season training."
McFarland said: "Bill is a very exciting young prospect who, for a number of reasons, has had limited playing opportunities over the past couple of years.
"He obviously feels now is the right time for a new challenge in his career and he will bring enthusiasm and unquestionable talent to our squad. We’re confident that he’ll be a really good addition."