The Northern Irishman extended his 12-fight unbeaten record with a convincing win at the Titanic Exhibition Centre.
All three ringside judges scored the 10-round contest in favour of McCullagh, 28, with wide scores of: 99-91, 98-92, 96-94.
On an undercard packed with local talent, Marco McCullough clinched the vacant IBO super featherweight title. Belfast-native McCullough, 28, beat veteran Dominican Ruddy Encarnacion, 39, in a thrilling fight to claim his fourth consecutive win and extend his record to 21-4.
In the only other title fight on the card, Paddy Gallagher stopped Dubliner Jay Byrne in the fourth round of their BUI Celtic welterweight title contest. Pat-man wants the winner of Gary Corcoran vs Johnny Garton next, who both meet for the British welterweight title on October 20.
There were also victories for Sean McComb, Steven Ward and Steven Donnelly.
Light heavyweight Ward extended his perfect professional record to 9-0 when his opponent, Rolando Paredes of Mexico, was disqualified for headbutting.
Two-time Commonwealth bronze medallist Donnelly and McComb, who both turned professional this year, registered their third consecutive wins, beating Arvydas Trizno and Petar Alexandrov, respectively.