UK light heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a contest where the techniques failed to mesh, with constant grabbing marring the fight.
The officials had it 96-94 for to the winner, with the third a even score.
"It wasn't my best display but what do champions do? They succeed," the victor said in the ringside as he was greeted with negative reactions from the spectators.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in February - to claim a 20th pro success.
Various analysts believed Parker, thirty-one, merited the decision but the British boxer suffered the second setback of his 28-fight professional journey.
Buatsi Claims Win in Dull Match
The fighter's advancement has plateaued in recent times through management issues and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers prepared to take risks in a cagey early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand mid-fight, was participating in his second bout at the higher weight class.
By the halfway stage, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the more effective stanzas.
The crowd's patience diminished during constant clinching, with Parker falling to the floor multiple occasions during close exchanges.
The underdog finished the stronger, but several stanzas were hard to judge. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Arthur defeated Bradley Rea by split-decision in a terrific local rivalry contest to secure the European light-heavyweight championship.
The venue grew hushed for a extremely emotional homage before the fight as a bell ceremony tolled in honor of the city's native Hatton, who passed away at age 46 in September.
It was the premier televised boxing event in the location since the passing of Hatton. As the concluding sound faded, the quiet became a chant of "there's only one Ricky Hatton".
The action during the bout matched the feeling. The eventual winner was knocked down by a powerful punch squarely on the jaw in the initial stage, standing uncertainly to his feet on the eight count.
But the red-colored shorts of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was damaged early, noticeable damage developing under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over the full distance.
The victor edged the verdict with judges scorecards of even score, narrow lead and wider gap, but each competitor were relentless and brave, everything their inspiration the legend embodied.
