Liam Kerrigan has joined UCD from Sligo Rovers, with the Bit O' Red snapping up Accrington Stanley forward Niall Watson as a replacement.
Kerrigan becomes the second Sligo player to join the Students on a scholarship this month following Jack Keaney's move.
Kerrigan made 24 senior appearance for the Bit O' Red after progressing from their Under-17 side.
The 19-year-old said: "Like Jack said this has been a very difficult decision to make. I don't remember a time when I wasn’t a Sligo Rovers fan and making my debut and signing my first professional contract last year was a dream come true.
"I'd also like to thank everyone behind the scenes at Sligo Rovers and all the fans for supporting me over the last two seasons.
"Best of luck to everyone at the club for the rest of the season."
Sligo boss Liam Buckley said: "Liam has decided to take up this offer. We wish him well. We don’t want to lose our young players and going forward the IT Sligo scholarship scheme will help with that.
"It’s disappointing but we wish Liam a great future and perhaps one day we will see him in a Sligo Rovers jersey again."
Meanwhile, Rovers have taken fellow 19-year-old Watson on a loan switch from League 1 Accrington.
He played in a friendly match in Sligo for his parent club earlier this month.
Buckley added: "I spoke with John Coleman and it's a good move for all parties.
"He has been involved with Accrington’s first-team and at a couple of non-league clubs.
"He can play in an attacking role on the left or right, so we’ll give him a chance in training to impress and force a way into the side.
"In terms of other signings, the market is not favourable at this time of year in Ireland but we remain in the hunt.
"We’re exploring things but it has to be a player that is really going to improve us. I won’t sign someone if it isn’t right for us. There’s less than two weeks left, we’ll see how things go."