British light heavyweight Buatsi secured a victory yet unimpressive debut to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a close ten-round bout at the Manchester venue.
But the challenger landed significant shots, delivering effective single shots in a match where the techniques didn't complement each other, with excessive holding marring the contest.
The scoring judges judged it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my best showing but what defines champions? They win," the victor said in the ring as he was greeted with boos from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th pro success.
Some ringside observers felt the challenger, 31, merited the decision but the British boxer endured the second loss of his 28-bout career.
The Champion Secures Triumph in Uneventful Encounter
The fighter's advancement has stalled in recent years through management issues and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with neither fighter ready to take risks in a tentative early stages.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second bout at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a tight guard to narrowly win the more effective rounds.
The spectators' acceptance diminished amid frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
Parker ended stronger, but multiple periods were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian star Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Homage Motivates Manchester Derby Battle
In the supporting bout, Arthur beat Bradley Rea by split-decision in a terrific local rivalry contest to secure the European light heavyweight title.
The stadium became quiet for a deeply poignant tribute before the fight as 10 bells tolled in honor of the city's native Hatton, who succumbed 46 years old in last month.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the stillness became a chant of "there's just one Ricky Hatton".
The competition within the ring matched the sentiment. The eventual winner was floored by a left hook flush on the jaw in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon came forward again. Across the ring, the opponent - in opposing blue - was injured quickly, significant bruising appearing under his eye as the pair landed punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over twelve rounds.
The victor narrowly won the decision with judges scorecards of even score, narrow lead and wider gap, but both fighters were determined and full of heart, exactly what their hero the legend stood for.
