A brace from Cork City's Mark O’Mahony and a debut goal from Crystal Palace's Joseph Gibbard were enough to give Colin O’Brien’s team the win.
Ireland were ahead in the eighth minute when Franco Umeh was felled in the box and his club teammate, O’Mahony, stepped-up to score the resulting penalty.
Shortly after Sweden were level through Momodou Lamin Sonko but Ireland continued to push for their second goal with Umeh forcing Elis Bishesari into a save in the 26th minute. It was the last clear-cut chance of the half as both sides went in all square.
After the break Ireland flew out of the traps. Shamrock Rovers' Gideon Tetteh went close with an effort in the 46th minute but just two-minutes later Gibbard gave Ireland the lead when his strike from the edge of the box for a goal on his first game in an Irish jersey.
O’Mahony gave Ireland a two-goal lead in the 54th minute when his he was able to convert on the rebound following a save from Bishesari.
That sealed it as a contest with Ireland now heading into Friday’s game with Denmark full of confidence.
Republic of Ireland: Walsh, Curtis (C), O’Brien, McAlinney, Ferizaj, Gibbard, McManus, Bloxham (Lipsuic, 76), Umeh (Turley, 78), Tetteh (Hodgins, 76), O’Mahony (Mohan, 84)
Sweden: Bishesari, Alder, Makolli, Alvarez Perez, Hughes, Stroud, Avlander, Helm (C), Machowski Thorell, Sonko, Bangala.
Substitutes: Pettersson, Wester, Nwanege, Prica, Hodzic, Andrén, Isa, Agbonifo, De Oliveira
Referee: Antonio Melnjak (Croatia)
International Friendly Fixtures/Results (all kick-off times are Irish time)
Tuesday, November 15 | Republic of Ireland MU18 3-1 Sweden MU18
Friday, November 18 | Republic of Ireland MU18 v Denmark MU18, Poreč, Croatia, KO 4.30pm
Monday, November 21 | Croatia MU18 v Republic of Ireland MU18, Poreč, Croatia, KO 9.30am