Michael Conlan (11-0) cruised to an 11th straight win as he outpointed Mexico's Ruben Garcia Hernandez (24-4-2) at Madison Square Garden in New York.
The Northern Irishman, 27, was given a 100-90 verdict by all three judges in the WBO Inter-Continental featherweight title contest.
"We could have stepped on the gas but we tried out a few things tonight," said the World Amateur Championships Gold medalist after the fight.
Victory for Belfast's Conlan sets him up for a summer bout in his home city against Russian Vladimir Nikitin, who controversially defeated him at the 2016 Olympics in Rio.
Nikitin was in also action on the Madison Square Garden bill and had to work hard to earn a majority decision over US journeyman Juan Tapia in their six-round bout. One of the judges scored the fight a 57-57 draw with the other two handing the lucky Russian a 59-55 verdict.
The bad news on Ireland's national holiday was that Conlan's close friend Paddy Barnes (5-2) is now considering retirement after a valiant points defeat to Oscar Mojica (12-5-1) - his second straight loss - on the same bill.
Aiming to get his career on track after suffering his first professional defeat in a world flyweight title challenge by Cristofer Rosales last August, Barnes sustained a broken nose early in the opening round in the bantamweight contest against American Mojica.
As he moved up two weight divisions for the contest, Barnes, 32, was floored by a body shot in the second round, which bizarrely appeared to be ruled as a slip by the referee.
However, Mojica, 26, continued to dominate the six-round contest and Barnes admitted afterwards that he was fortunate to be given the verdict by one of the three judges as the unheralded American was adjudged a split-decision winner.
Two judges gave the fight 58-56 to Mojica, who has lost five of his 18 professional bouts, with Barnes getting a 58-56 verdict from the other judge.
"I don't know how they had it close. I thought he won every round," Barnes, who won Olympic bronze medals in 2008 and 2012, humbly told ESPN.
He told reporters: "To be honest, I will probably retire now. I don't think there is any point boxing on after a defeat like that.
"The fans were great but at the end of the day I have to take care of my health. If I am going to box like that, then what's the point boxing anymore? I can't contest for a world title with that performance."