UK light heavyweight Buatsi made a winning yet underwhelming start to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a majority decision in a tight 10-round bout at the Manchester venue.
But the challenger had his moments, landing some telling clean blows in a contest where the techniques didn't complement each other, with excessive holding marring the action.
The scoring judges had it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They win," the victor commented in the ringside as he was greeted with disapproval from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with Callum Smith in February - to secure a 20th pro success.
Some ringside observers thought Parker, thirty-one, deserved the victory but the British boxer suffered the second loss of his 28-match career.
Buatsi Claims Win in Uneventful Affair
Buatsi's progress has slowed in recent times through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - maybe in what seems like a last chance - under recent support.
He began cautiously, with both competitors willing to be aggressive in a calculated initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after suffering a hand injury during the bout, was competing in only his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, making life awkward for the favorite, who worked behind a solid defense to barely take the more effective periods.
The spectators' acceptance decreased amid frequent holding, with Parker falling to the floor multiple occasions during grappling.
The underdog closed well, but many rounds were difficult to score. However, ex-champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian star Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Memorial Motivates Manchester Derby Battle
In the secondary fight, Arthur defeated Rea by divided decision in a excellent Manchester vs Manchester contest to win the European light-heavyweight championship.
The stadium fell silent for a profoundly moving homage prior to the bout as a bell ceremony rang in remembrance of local hero Ricky Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the final chime ended, the quiet gave way to a chant of "there's only one Hatton".
The competition within the ring matched the emotion. The eventual winner was knocked down by a powerful punch flush on the chin in the early round, getting up unsteadily to his feet on the referee's count.
But the traditional red attire of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was marked up soon, noticeable damage developing under his face as the fighters traded punishing blows.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with effective uppercuts as the action rarely dropped over twelve rounds.
The victor barely secured the result with official scores of draw, close margin and clearer margin, but each competitor were determined and brave, exactly what their hero Hatton represented.
