UK light heavyweight Buatsi made a winning yet unimpressive debut to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a tight 10-round bout at the Co-op Live Arena.
But Parker found success, delivering effective clean blows in a match where the styles didn't complement each other, with frequent clinching marring the fight.
The scoring judges scored it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," Buatsi stated in the arena as he was greeted with negative reactions from the crowd.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts believed the challenger, thirty-one, merited the decision but the British boxer endured the second setback of his 28-bout career.
Buatsi Claims Win in Uneventful Encounter
The fighter's advancement has plateaued in recent times through contract problems and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to overcommit in a cagey early stages.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, causing problems for Buatsi, who worked behind a solid defense to barely take the better periods.
The audience's tolerance diminished amid frequent holding, with Parker slipping to the canvas various instances during clinches.
The underdog finished the stronger, but many rounds were challenging to assess. Nevertheless, former world champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
Buatsi progresses, but with the likes of power puncher Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Hatton Tribute Inspires Local Rivalry Battle
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a terrific Manchester vs Manchester contest to capture the continental title.
The venue grew hushed for a deeply poignant tribute prior to the bout as 10 bells rang in honor of the city's native Ricky Hatton, who passed away 46 years old in September.
It was the first major televised fight night in the location since the passing of Hatton. As the final chime ended, the quiet transitioned to a shout of "there's just one Hatton".
The competition during the bout matched the emotion. The eventual winner was floored by a significant blow flush on the chin in the initial stage, rising shakily to his feet on the referee's count.
But the red-colored attire of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was damaged early, heavy swelling appearing under his eye as the pair landed punishing blows.
Rea, 27, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action seldom decreased over 12 rounds.
Arthur edged the result with scoring tallies of 114-114, close margin and wider gap, but both fighters were relentless and courageous, everything their hero Hatton embodied.
