Leinster say they respect Jordi Murphy's decision to leave the province.
Ulster announced on Wednesday morning that the back row will join them on a two year deal at the end of the season.
Leinster Rugby Head Coach Leo Cullen admitted he was sad to see the talented 26-year-old: "Jordi is a hugely talented player and a very popular member within our squad.
"It is to his enormous credit that he has come back as strong as he has from his knee injury last year in Ireland's famous win over the All Blacks in Chicago.
"We respect Jordi's decision to move and everyone at Leinster wishes him the very best with his future.”
The Barcelona born back row spent seven-years with the Blues, making 95 appearances while crossing the line 17 times.
His game time has been impacted by injury and the fierce competition at the province. Murphy has been scrapping for starts against the likes of Sean O'Brien, Rhys Ruddock, Josh van der Flier, Dan Leavy and Jack Conan.
Director of Rugby Les Kiss says Ulster saw off significant competition to secure the services of the 26 year old, who has been capped 18 times for Ireland.
"Jordi has been on our radar for the past 12 months and it took a lot of hard work between his agent and Bryn (Cunningam, Operations Director, Ulster Rugby) to get this completed. Unsurprisingly, there was a lot of interest in Jordi and we are really pleased that he has chosen to ply his trade here in Belfast.
"The acquisition of Jordi for next season is great news for everyone connected with Ulster Rugby and I believe this move will greatly benefit both parties.
"He's an extremely talented player; an explosive runner and a nuisance at the breakdown, while his versatility allows him to play across the back row.
"At 26 years of age, we believe Jordi has the potential to play the best rugby of his career at Ulster and that is a hugely exciting prospect.
"As injuries are becoming increasingly common in the modern game, it's imperative that we continue to expand the playing resources we have available.
"With Marty Moore also on board, plus the return to fitness of Marcell Coetzee, we have added some much-needed depth to our pack for next season.
Explaining his decision to leave Leinster, Murphy said:
"Having considered my options at length, I realise that this represents a great opportunity for me to challenge for a position at Ulster and hopefully become a more regular feature in the national set-up.
"Ulster is building a strong squad for next season and I'm really looking forward to the new challenge. However, I am fully focused on contributing as best I can for Leinster for the remainder of the current campaign."