British light heavyweight Buatsi secured a victory yet unimpressive start to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a tight 10-round contest at the Manchester venue.
But Parker found success, delivering effective individual punches in a fight where the styles didn't complement each other, with constant grabbing marring the fight.
The officials had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my best display but how do champions respond? They win," Buatsi said in the arena as he was met by boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in February - to claim a twentieth professional win.
Some ringside observers felt the challenger, 31, deserved the decision but the contender suffered the second loss of his 28-bout career.
The Champion Earns Triumph in Dull Encounter
Buatsi's progress has plateaued in recent times through contract problems and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter ready to take risks in a calculated initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after damaging his hand in the contest, was participating in 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 protective stance to narrowly win the cleaner stanzas.
The spectators' acceptance decreased during regular grabbing, with Parker going down multiple occasions during close exchanges.
The underdog closed well, but multiple periods were difficult to score. Nevertheless, former world champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of hard hitter David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Fight
In the secondary fight, Arthur defeated Bradley Rea by split-decision in a excellent Manchester vs Manchester contest to capture the continental championship.
The stadium grew hushed for a deeply poignant memorial before the fight as ten bells tolled in memory of the city's native Ricky Hatton, who died aged 46 in recently.
It was the premier televised match card in the city since Hatton's death. As the last bell ended, the quiet transitioned to a shout of "there's only one Hatton".
The competition within the ring matched the feeling. The eventual winner was floored by a left hook squarely on the chin in the early round, getting up unsteadily to his position on the eight count.
But the red-colored attire of the fighter soon advanced again. From the other corner, Rea - in competitive blue - was injured quickly, significant bruising developing under his eye as the duo landed punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
The victor narrowly won the decision with judges scorecards of even score, 115-113 and wider gap, but both fighters were persistent and courageous, all the qualities their inspiration the legend stood for.
