Belfast's Olympic medallists Paddy Barnes and Michael Conlan both won their finals at the Irish Amateur Championships in Dublin on Friday.
Barnes took a seventh light-flyweight crown with a unanimous verdict over defending champion Hughie Myers.
Conlan collected his fourth Irish title in a row by beating Donegal fighter Tyrone McCullough at bantamweight.
Welterweight Stephen Donnelly, of All Saints, Ballymena, beat London Olympian Adam Nolan on a split decision.
However, Holy Trinity lightweight Sean McComb lost on a split decision to David Oliver Joyce at the National Stadium.
Monkstown fighter Steven Ward was the last Ulster boxer in action and he went down 2-1 to Gary Sweeney in the heavyweight division.
Conlan becomes the first fighter since Damaen Kelly to win national senior titles at flyweight and bantamweight, while Donnelly was named best boxer following his victory over Nolan.