UK light heavyweight Buatsi earned a win yet unimpressive beginning to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a majority decision in a close 10-round fight at the boxing arena.
But the challenger had his moments, delivering effective clean blows in a fight where the styles didn't complement each other, with constant grabbing marring the action.
The officials had it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best performance but what do champions do? They prevail," Buatsi said in the ring as he was met by boos from the spectators.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Some ringside observers believed the challenger, 31, deserved the decision but the Derbyshire fighter endured the second defeat of his 28-match career.
The Champion Earns Triumph in Uneventful Match
The fighter's advancement has plateaued in recent years through contract problems and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now stands trying to realize his potential - maybe in what appears to be a last chance - under new promotional backing.
He opened tentatively, with neither fighter prepared to be aggressive in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was competing in only his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who utilized a protective stance to barely take the better periods.
The spectators' acceptance decreased because of frequent holding, with Parker falling to the floor multiple occasions during grappling.
Parker finished the stronger, but many rounds were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi moves on, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Tribute Fuels Manchester Derby Battle
In the secondary fight, Arthur defeated Rea by split-decision in a excellent all-Manchester contest to capture the European light-heavyweight championship.
The venue grew hushed for a deeply poignant tribute before the fight as 10 bells rang in honor of local hero Ricky Hatton, who succumbed at age 46 in last month.
It was the premier televised match card in the city since Hatton's passing. As the final chime faded, the quiet became a chant of "only one Hatton".
The action during the bout reflected the sentiment. Arthur was sent to the canvas by a left hook directly to the jaw in the initial stage, rising shakily to his feet on the referee's count.
But the Manchester United-red shorts of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was damaged early, significant bruising developing under his orbital area as the fighters exchanged punishing blows.
Rea, twenty-seven, connected with strong blows but the champion, 34, responded in kind with stinging uppercuts as the pace hardly diminished over twelve rounds.
The victor edged the result with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were determined and full of heart, all the qualities their inspiration the legend embodied.
