UK light heavyweight Buatsi secured a victory yet disappointing beginning to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a competitive 10-round contest at the Co-op Live Arena.
But Parker landed significant shots, delivering effective clean blows in a match where the styles didn't complement each other, with constant grabbing marring the action.
Two judges had it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest display but what defines champions? They prevail," Buatsi stated in the ringside as he was met by negative reactions from the audience.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in February - to claim a 20th pro success.
Various analysts thought Parker, 31, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-match professional journey.
Buatsi Earns Victory in Uneventful Match
His career development has slowed in recent years through management issues and long spells of inactivity.
Previously predicted as the next star of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He began cautiously, with the two boxers prepared to take risks in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second bout at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for Buatsi, who worked behind a tight guard to narrowly win the cleaner periods.
The spectators' acceptance diminished amid constant clinching, with the challenger falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but several stanzas were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor advances, but with the likes of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Contest
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a excellent local rivalry battle to win the European light-heavyweight belt.
The venue grew hushed for a extremely emotional homage before the fight as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in recently.
It was the first major televised fight night in the city since Hatton's death. As the final chime ended, the stillness transitioned to a roar of "there's only one Ricky Hatton".
The fighting during the bout reflected the sentiment. The eventual winner was knocked down by a powerful punch flush on the face in the early round, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, the opponent - in competitive blue - was marked up soon, significant bruising forming under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
The victor narrowly won the decision with official scores of even score, close margin and clearer margin, but each competitor were relentless and courageous, all the qualities their inspiration Hatton embodied.
