Ireland lost the toss and were asked to bat first, but through the fruitful pairing of Balbirnie and Stirling they moved to 109 before the latter was dismissed by Gudakesh Motie.
Cade Carmichael, who was making his debut alongside Tom Mayes and Liam McCarthy, was out for 16, but Harry Tector managed 56 with Lorcan Tucker also adding 30 to help Ireland set a high target.
Mayes claimed his first wicket for Ireland as he dismissed West Indies captain Shai Hope in the powerplay and the difficulties continued as West Indies slipped to 31-5 in the powerplay before Roston Chase (55) and Matthew Forde (38) steadied their innings.
McCarthy removed Brandon King, Keacy Carty, Amir Jangoo and Forde as the West Indies were bowled out for 179 with 15.5 overs remaining, falling to a 124-run defeat.
“We want to win this series of course, but you have to enjoy these sorts of results. It is a huge win for us, and I think the confidence is going to be high going into the weekend,” said Balbirnie.
