British light heavyweight Buatsi secured a victory yet unimpressive debut to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a close 10-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful clean blows in a fight where the techniques failed to mesh, with constant grabbing spoiling the action.
Two judges had it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my best performance but what do champions do? They win," the victor stated in the ring as he was faced negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th career victory.
Some ringside observers believed the challenger, 31, deserved the win but the British boxer experienced the second setback of his 28-fight professional journey.
Buatsi Secures Win in Uneventful Encounter
The fighter's advancement has stalled in the past few years through management issues and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter prepared to take risks in a tentative opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was making just his second appearance at light heavyweight.
By the middle rounds, Parker had kept it close, making life awkward for the favorite, who utilized a solid defense to edge the cleaner stanzas.
The audience's tolerance diminished because of frequent holding, with Parker slipping to the canvas several times during clinches.
The underdog ended stronger, but multiple periods were difficult to score. Although, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Memorial Inspires Manchester Derby Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester contest to secure the European light-heavyweight title.
The arena fell silent for a profoundly moving memorial before the fight as a bell ceremony tolled in honor of the city's native Ricky Hatton, who died at age 46 in last month.
It was the premier televised match card in the urban center since the passing of Hatton. As the concluding sound faded, the stillness transitioned to a chant of "there's just one Hatton".
The action within the ring matched the feeling. Arthur was floored by a left hook directly to the jaw in the early round, standing uncertainly to his feet on the eight count.
But the Manchester United-red equipment of Arthur soon advanced again. From the other corner, the opponent - in rival City blue - was damaged soon, noticeable damage appearing under his eye as the pair traded hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action seldom decreased over the full distance.
The victor narrowly won the result with scoring tallies of 114-114, close margin and 115-112, but both fighters were relentless and brave, everything their hero the legend represented.
