UK light heavyweight Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a close ten-round bout at the Manchester venue.
But the challenger landed significant shots, delivering effective single shots in a contest where the techniques never quite clicked, with constant grabbing disrupting the action.
The scoring judges judged it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but what defines champions? They prevail," the victor commented in the arena as he was faced negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th pro success.
Various analysts thought Parker, 31, deserved the victory but the Derbyshire fighter experienced the second loss of his 28-bout professional journey.
Buatsi Secures Triumph in Dull Encounter
His career development has slowed in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now stands trying to realize his potential - maybe in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to be aggressive in a tentative initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was making just his second bout at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for the favorite, who utilized a tight guard to edge the better rounds.
The audience's tolerance wore thin amid constant clinching, with Parker falling to the floor several times during clinches.
The underdog closed well, but multiple periods were hard to judge. However, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the likes of heavy hitter David Benavidez, and Russian star Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Tribute Motivates Manchester Derby Fight
In the supporting bout, Arthur beat Bradley Rea by split-decision in a outstanding all-Manchester contest to capture the continental belt.
The stadium became quiet for a deeply poignant homage before the fight as a bell ceremony rang in remembrance of Manchester's own Hatton, who died at age 46 in last month.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the concluding sound faded, the silence gave way to a shout of "only one Ricky Hatton".
The action within the ring reflected the emotion. Arthur was knocked down by a powerful punch directly to the face in the early round, getting up unsteadily to his feet on the referee's count.
But the traditional red attire of the fighter soon came forward again. Across the ring, Rea - in opposing blue - was damaged early, heavy swelling forming under his face as the fighters exchanged punishing blows.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over the full distance.
Arthur edged the verdict with judges scorecards of draw, narrow lead and wider gap, but each competitor were relentless and courageous, exactly what their idol Hatton stood for.
