The move was first reported at the start of the year, with the IRFU eager to get the loosehead prop more regular game time.
It’s been quite a fall for McGrath who played in all three British and Irish Lions test matches against New Zealand just two years ago, albeit coming on as a substitute in each one.
RugbyPass now understands that the deal has been agreed and that it is set to be confirmed publically.
The 54-times capped Irish international has found playing time hard to come by this season, with Cian Healy enjoying a renaissance in his playing career, just a year or two after it was thought injuries could see the dynamic prop forced into an early retirement.
McGrath, 29, is under contract with Leinster and the IRFU until the summer of 2020, but according to previous reports, both he and the IRFU are frustrated at his lack of opportunities in the capital and that a move north to Ulster could solve the problem.
Ulster have found themselves undermanned in the front row at times this season and the addition of McGrath would come as welcome relief to their stock of looseheads.
The prop has spent his entire professional career with Leinster to date and he played a crucial role in many of the province’s successes since he joined in 2010, including helping guide the side to the Guinness PRO14 and European Rugby Champions Cup double in 2018.
Hip surgery in November has impacted McGrath’s season with Leinster and Ireland, although he was used as a replacement in Ireland’s 26-16 victory over Italy in Rome.
Sign up to our mailing list here and we’ll keep you up to the minute with weekly updates from the world of rugby.