UK light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a competitive 10-round bout at the boxing arena.
But Parker landed significant shots, landing some telling single shots in a match where the styles failed to mesh, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest display but what defines champions? They win," the victor said in the ringside as he was met by negative reactions from the crowd.
The British fighter bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a twentieth professional win.
Several boxing experts felt Parker, thirty-one, deserved the decision but the British boxer experienced the second setback of his 28-fight career.
Buatsi Earns Win in Uneventful Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and extended periods of lack of fights.
Earlier forecast as the future of UK boxing, he now finds himself trying to realize his potential - perhaps in what seems like a ultimate opportunity - under recent support.
He started carefully, with both competitors willing to take risks in a cagey opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after breaking his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a tight guard to narrowly win the cleaner rounds.
The audience's tolerance diminished during frequent holding, with the challenger slipping to the canvas various instances during clinches.
Parker finished the stronger, but many rounds were hard to judge. Nevertheless, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Memorial Fuels Manchester Derby Fight
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester battle to capture the European light-heavyweight belt.
The venue grew hushed for a profoundly moving memorial prior to the bout as ten bells tolled in memory of Manchester's own Ricky Hatton, who died at age 46 in recently.
It was the first major televised boxing event in the city since Hatton's death. As the last bell disappeared, the quiet became a chant of "there's just one Ricky Hatton".
The fighting inside the ropes reflected the feeling. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the initial stage, standing uncertainly to his footing on the referee's count.
But the Manchester United-red shorts of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was damaged soon, significant bruising developing under his orbital area as the duo exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity hardly diminished over 12 rounds.
Arthur barely secured the decision with judges scorecards of even score, narrow lead and clearer margin, but each competitor were determined and full of heart, exactly what their hero the legend stood for.
