UK light heavyweight Buatsi made a winning yet disappointing debut to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a split decision in a competitive ten-round contest at the boxing arena.
But the challenger landed significant shots, connecting with powerful individual punches in a match where the styles failed to mesh, with excessive holding disrupting the contest.
The officials had it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest showing but what defines champions? They prevail," the victor said in the ring as he was faced negative reactions from the spectators.
The Londoner returned to winning ways after his first professional defeat - an epic battle with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts felt Parker, 31, deserved the victory but the contender experienced the second defeat of his 28-match professional journey.
Buatsi Earns Triumph in Slow Match
His career development has slowed in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the next star of the British fight scene, he now is positioned trying to achieve expectations - maybe in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers ready to take risks in a cagey opening few rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who utilized a protective stance to narrowly win the cleaner periods.
The spectators' acceptance decreased during regular grabbing, with Parker falling to the floor multiple occasions during close exchanges.
Parker ended stronger, but several stanzas were hard to judge. Nevertheless, previous titleholder Carl Frampton - commentating on Dazn - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Russian champion Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Tribute Fuels Manchester Derby Fight
In the supporting bout, Arthur overcame Rea by split-decision in a terrific Manchester vs Manchester fight to secure the continental championship.
The stadium became quiet for a profoundly moving homage prior to the bout as ten bells sounded in remembrance of local hero Hatton, who succumbed aged 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the concluding sound ended, the silence gave way to a shout of "there's only one Ricky Hatton".
The competition within the ring equaled the sentiment. Arthur was sent to the canvas by a left hook directly to the chin in the initial stage, getting up unsteadily to his position on the eight count.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, the opponent - in opposing blue - was injured quickly, significant bruising appearing under his eye as the duo exchanged powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor barely secured the decision with scoring tallies of draw, narrow lead and 115-112, but each competitor were persistent and brave, all the qualities their inspiration the legend embodied.
