Ireland back row Jordi Murphy will join Ulster next summer on a two-year contract.
Ulster have beaten off competition to secure the services of Murphy as they make further plans on the back of the news Wasps prop Marty Moore will also move to Belfast
Murphy said: "It's been an incredibly hard decision to leave Leinster, where I have made some great friends and enjoyed some fantastic times, but I am excited by the prospect of moving north and linking up with some familiar faces.
"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."
Ulster director of rugby Les Kiss said it was a long-term plan to secure Murphy’s services.
"Jordi has been on our radar for the past 12 months and it took a lot of hard work between his agent and Bryn Cunningamto 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.
"The increased investment in our Academy forwards is starting to pay off and five of those in our current system - Nick Timoney, Adam McBurney, Aaron Hall, Greg Jones and Matthew Dalton - have played for the senior team already this season. That's another positive sign for the future of rugby in Ulster.".
Murphy has made 18 Ireland appearances to date, with his most recent coming in the win versus Fiji last month.