UK light heavyweight Buatsi secured a victory yet underwhelming debut to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a tight 10-round bout at the boxing arena.
But the challenger had his moments, connecting with powerful clean blows in a match where the techniques didn't complement each other, with excessive holding disrupting the contest.
Two judges judged it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my finest showing but what do champions do? They win," Buatsi commented in the ring as he was greeted with boos from the audience.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to claim a 20th pro success.
Various analysts believed Parker, thirty-one, should have been awarded the victory but the contender experienced the second loss of his 28-match career.
The Champion Claims Triumph in Dull Match
The fighter's advancement has slowed in the past few years through management issues and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - maybe in what seems like a final roll of the dice - under fresh management.
He opened tentatively, with neither fighter willing to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after breaking his hand during the bout, was making just his second appearance at light heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who utilized a protective stance to narrowly win the better stanzas.
The audience's tolerance diminished because of regular grabbing, with the challenger falling to the floor multiple occasions during grappling.
The underdog ended stronger, but many rounds were hard to judge. However, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
Buatsi progresses, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Tribute Inspires Manchester Derby Contest
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a excellent local rivalry fight to capture the European light heavyweight championship.
The arena grew hushed for a profoundly moving tribute ahead of the contest as 10 bells rang in remembrance of the city's native Hatton, who died 46 years old in September.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the last bell ended, the silence became a shout of "there's just one Hatton".
The action during the bout matched the emotion. Arthur was knocked down by a significant blow flush on the jaw in the initial stage, rising shakily to his position on the eight count.
But the traditional red attire of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was injured quickly, heavy swelling forming under his face as the pair traded punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the action hardly diminished over twelve rounds.
The victor edged the verdict with scoring tallies of draw, narrow lead and 115-112, but the two athletes were determined and courageous, all the qualities their inspiration Hatton stood for.
