British light-heavyweight Buatsi earned a win yet unimpressive beginning to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a competitive ten-round contest at the boxing arena.
But Parker found success, landing some telling single shots in a match where the approaches didn't complement each other, with excessive holding spoiling the fight.
Two judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my best showing but what defines champions? They succeed," Buatsi stated in the arena as he was faced disapproval from the crowd.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Some ringside observers believed Parker, thirty-one, should have been awarded the win but the British boxer experienced the second loss of his 28-match professional journey.
The Champion Secures Win in Dull Encounter
His career development has plateaued in recent times through management issues and considerable time of lack of fights.
Previously predicted as the rising talent of the British fight scene, he now stands trying to achieve expectations - maybe in what feels like a last chance - under new promotional backing.
He opened tentatively, with the two boxers ready to take risks in a tentative opening few rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second bout at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who utilized a tight guard to edge the cleaner stanzas.
The audience's tolerance diminished because of frequent holding, with the challenger going down various instances during grappling.
The underdog finished the stronger, but multiple periods were difficult to score. However, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Motivates All-Manchester Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding all-Manchester contest to win the European light-heavyweight championship.
The venue fell silent for a deeply poignant homage ahead of the contest as a bell ceremony rang in memory of Manchester's own Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the location since Hatton's death. As the final chime ended, the silence gave way to a roar of "there's just one Hatton".
The fighting inside the ropes matched the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the second round, getting up unsteadily to his footing on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. Across the ring, the opponent - in rival City blue - was marked up soon, heavy swelling developing under his eye as the duo landed powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the intensity hardly diminished over twelve rounds.
The victor narrowly won the decision with official scores of draw, 115-113 and 115-112, but both fighters were persistent and full of heart, all the qualities their hero Hatton stood for.
