A first-half penalty from Cruz Allen and a finish from Eliott Myles late on was enough to condemn Ireland to a defeat at Dragon Park despite a late goal on his Ireland debut by Tommy Lillis.
Head Coach Jason Donohue named Shamrock Rovers defender James Roche as captain and gave an Ireland debut to Ipswich Town forward Afi Adebayo.
The first half started as a balanced affair with Ireland finding a lot of success down the right-hand side through Christian Donlon-Goncalvez.
Wales' main threat came from set-pieces but the Irish backline was able to keep the hosts at bay.
But Wales were awarded a penalty in the 28 minute when Ireland were adjudged to have committed a foul. Allen stepped-up to give his side the lead, a lead they held onto going into the break.
At half-time Ike Orazi was introduced in replace of Matthew Moore as Ireland went looking for a way back in the game.
Fifteen minutes in the second half Ireland were handed a lifeline when Caio Ifans was shown a red card for persistent fouling. However the hosts doubled their lead in the 70th minute when Myles found the corner with a low effort inside the 18-yard box.
Ireland pulled a goal back in the final minute when Lillis scored on his Ireland debut, two minutes after coming on the field. The Galway United defender headed home an Orazi cross to half the deficit but his effort came too late for an Ireland recovery.
Wales: Hudson, Apakio, Ifans, Clarke, Popham, Walker-Smith, Stevens, Bradbury, Myles, Allen, Bostock.
Substitutes: Seagar, Jones, Phillips, Clarke, Picotto, Perry, Salmon, Barton, King-Phillips
Republic of Ireland: Ellis: Roche, Mulligan (Coffey 78), Matthew Moore (Orazi 41), Donlon-Goncalves (Hannon 60), O'Donnell (Lillis 78), Adebayo (Marshall 55), Fitzgerald, Harnett, Sean Moore, O'Sullivan.
Referee: Ieuan Davies (Wales)
International Friendly Fixture
Thursday, March 17 | Wales MU15s v Republic of Ireland MU15s, Dragon Park, Newport Wales, KO 12pm