UK light heavyweight Buatsi earned a win yet underwhelming debut to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close ten-round contest at the Co-op Live Arena.
But the challenger had his moments, landing some telling clean blows in a match where the styles didn't complement each other, with constant grabbing marring the action.
The officials scored it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my greatest performance but how do champions respond? They succeed," Buatsi said in the ringside as he was greeted with boos from the crowd.
The Londoner got back to winning after his maiden career setback - an thrilling contest with his previous opponent in February - to claim a twentieth professional win.
Various analysts believed Parker, 31, merited the win but the British boxer suffered the second setback of his 28-fight professional journey.
Buatsi Claims Triumph in Uneventful Encounter
The fighter's advancement has stalled in recent times through management issues and long spells of inactivity.
Earlier forecast as the rising talent of UK boxing, he now stands trying to realize his potential - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with neither fighter willing to be aggressive in a calculated initial rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a tight guard to narrowly win the more effective rounds.
The audience's tolerance decreased because of frequent holding, with the challenger falling to the floor various instances during grappling.
The underdog finished the stronger, but multiple periods were difficult to score. Nevertheless, previous titleholder Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor advances, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - judging by this showing - still looks steep.
Hatton Homage Fuels Local Rivalry Fight
In the supporting bout, Lyndon Arthur beat Rea by split-decision in a terrific local rivalry contest to secure the European light-heavyweight belt.
The arena fell silent for a profoundly moving homage before the fight as 10 bells sounded in honor of Manchester's own Ricky Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound disappeared, the silence transitioned to a chant of "there's just one Hatton".
The fighting inside the ropes reflected the sentiment. The eventual winner was knocked down by a powerful punch directly to the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red equipment of the fighter soon advanced again. On the opposite side, the opponent - in opposing blue - was marked up early, heavy swelling appearing under his orbital area as the fighters traded hard punches.
Rea, 27, landed power punches but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity hardly diminished over 12 rounds.
Arthur barely secured the decision with official scores of 114-114, close margin and clearer margin, but each competitor were determined and brave, all the qualities their idol Hatton represented.
