UK light-heavyweight Buatsi earned a win yet underwhelming debut to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a close 10-round contest at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a contest where the styles didn't complement each other, with constant grabbing marring the fight.
The officials had it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest showing but what defines champions? They win," Buatsi commented in the ringside as he was faced boos from the crowd.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to earn a 20th pro success.
Some ringside observers believed Parker, thirty-one, should have been awarded the win but the contender endured the second loss of his 28-bout professional journey.
Buatsi Secures Win in Slow Match
The fighter's advancement has plateaued in recent times through management issues and long spells of inactivity.
Earlier forecast as the future of the British fight scene, he now stands trying to achieve expectations - possibly in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter willing to be aggressive in a cagey opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand in the contest, was competing in only his second appearance at the higher weight class.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who operated with a solid defense to barely take the better stanzas.
The crowd's patience diminished during regular grabbing, with the challenger going down several times during close exchanges.
Parker finished the stronger, but many rounds were difficult to score. Although, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the likes of power puncher David Benavidez, and Russian star Bivol leading the category, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Fight
In the supporting bout, Lyndon Arthur defeated Rea by split-decision in a terrific Manchester vs Manchester contest to win the European light-heavyweight championship.
The arena grew hushed for a deeply poignant homage before the fight as 10 bells sounded in memory of the city's native Ricky Hatton, who died at age 46 in last month.
It was the initial significant broadcast fight night in the city since Hatton's death. As the last bell disappeared, the stillness became a roar of "there's only one Ricky Hatton".
The action inside the ropes equaled the sentiment. The eventual winner was floored by a powerful punch flush on the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the red-colored attire of the fighter soon came forward again. On the opposite side, Rea - in rival City blue - was injured early, significant bruising developing under his orbital area as the duo landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur narrowly won the verdict with scoring tallies of even score, narrow lead and 115-112, but both fighters were relentless and full of heart, everything their hero the legend embodied.
