UK light-heavyweight Buatsi earned a win yet unimpressive debut to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a tight 10-round fight at the Manchester venue.
But the challenger had his moments, delivering effective clean blows in a fight where the techniques never quite clicked, with constant grabbing marring the contest.
The officials scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my finest performance but what defines champions? They prevail," the victor stated in the ring as he was met by boos from the audience.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Various analysts thought Parker, thirty-one, merited the win but the contender experienced the second setback of his 28-fight professional journey.
Buatsi Claims Win in Uneventful Affair
His career development has plateaued in recent times through management issues and extended periods of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to achieve expectations - maybe in what seems like a final roll of the dice - under recent support.
He opened tentatively, with both competitors ready to take risks in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who worked behind a tight guard to narrowly win the cleaner stanzas.
The spectators' acceptance diminished because of constant clinching, with Parker going down several times during grappling.
The underdog closed well, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the likes of power puncher David Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Memorial Motivates All-Manchester Fight
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a outstanding all-Manchester battle to capture the European light heavyweight championship.
The arena grew hushed for a profoundly moving memorial prior to the bout as ten bells sounded in remembrance of local hero Ricky Hatton, who passed away at age 46 in September.
It was the first major televised match card in the location since Hatton's death. As the last bell ended, the silence became a chant of "there's just one Ricky Hatton".
The competition during the bout matched the sentiment. Arthur was floored by a powerful punch directly to the chin in the early round, getting up unsteadily to his feet on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up early, significant bruising forming under his orbital area as the duo landed punishing blows.
Rea, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action seldom decreased over the full distance.
The victor narrowly won the decision with official scores of draw, narrow lead and 115-112, but both fighters were relentless and full of heart, all the qualities their hero the legend stood for.
