UK light heavyweight Buatsi secured a victory yet unimpressive debut to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a close 10-round bout at the boxing arena.
But the challenger landed significant shots, landing some telling single shots in a fight where the techniques didn't complement each other, with frequent clinching disrupting the fight.
The scoring judges judged it 96-94 to the winner, with the third a even score.
"It wasn't my greatest display but what defines champions? They win," Buatsi stated in the arena as he was greeted with negative reactions from the audience.
The Londoner bounced back after his initial pro loss - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Some ringside observers believed the challenger, 31, deserved the win but the Derbyshire fighter suffered the second loss of his 28-fight professional journey.
Buatsi Secures Triumph in Uneventful Encounter
His career development has stalled in recent years through contract problems and long spells of lack of fights.
Previously predicted as the next star of the British fight scene, he now finds himself trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter ready to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, making life awkward for the favorite, who utilized a solid defense to narrowly win the better periods.
The audience's tolerance decreased during regular grabbing, with Parker going down various instances during close exchanges.
Parker closed well, but multiple periods were challenging to assess. Nevertheless, former world champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for Parker, giving Buatsi just one round.
Buatsi moves on, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - on this evidence - still looks steep.
Hatton Homage Motivates All-Manchester Fight
In the supporting bout, Lyndon Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester fight to win the European light heavyweight belt.
The arena fell silent for a extremely emotional homage before the fight as ten bells sounded in remembrance of the city's native Hatton, who died aged 46 in recently.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the final chime ended, the silence transitioned to a chant of "there's just one Hatton".
The competition inside the ropes reflected the feeling. Arthur was floored by a significant blow directly to the jaw in the second round, getting up unsteadily to his feet on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was injured quickly, significant bruising forming under his eye as the duo landed punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over 12 rounds.
Arthur barely secured the verdict with official scores of even score, 115-113 and 115-112, but each competitor were determined and courageous, everything their hero the legend represented.
