UK light heavyweight Buatsi made a winning yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a competitive 10-round contest at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a match where the techniques failed to mesh, with excessive holding spoiling the fight.
Two judges had it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest showing but what do champions do? They succeed," Buatsi stated in the ringside as he was faced negative reactions from the spectators.
The Londoner returned to winning ways after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers thought Parker, 31, deserved the victory but the British boxer experienced the second defeat of his 28-bout career.
The Champion Secures Triumph in Slow Encounter
Buatsi's progress has stalled in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under recent support.
He started carefully, with neither fighter prepared to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to narrowly win the more effective periods.
The spectators' acceptance wore thin during regular grabbing, with the challenger slipping to the canvas various instances during clinches.
The underdog finished the stronger, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
The victor progresses, but with the likes of heavy hitter Benavidez, and Russian champion Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Hatton Homage Fuels Manchester Derby Fight
In the co-main event, Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry contest to win the continental championship.
The stadium grew hushed for a extremely emotional tribute prior to the bout as 10 bells sounded in remembrance of local hero Ricky Hatton, who succumbed aged 46 in last month.
It was the premier televised match card in the location since Hatton's passing. As the concluding sound disappeared, the quiet became a roar of "only one Ricky Hatton".
The fighting within the ring matched the sentiment. The eventual winner was knocked down by a left hook directly to the face in the second round, rising shakily to his footing on the referee's count.
But the Manchester United-red shorts of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was marked up quickly, significant bruising forming under his face as the pair traded hard punches.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor edged the verdict with scoring tallies of even score, close margin and clearer margin, but the two athletes were relentless and brave, exactly what their hero Hatton stood for.
