British light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a judges' verdict in a close 10-round bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a match where the approaches failed to mesh, with frequent clinching disrupting the action.
Two judges scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest performance but how do champions respond? They succeed," the victor commented in the ring as he was greeted with boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to claim a 20th pro success.
Some ringside observers believed Parker, thirty-one, deserved the win but the Derbyshire fighter endured the second loss of his 28-bout professional journey.
Buatsi Secures Triumph in Uneventful Match
The fighter's advancement has plateaued in recent times through promotional disputes and extended periods of lack of fights.
Earlier forecast as the future of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under recent support.
He began cautiously, with both competitors willing to overcommit in a tentative opening few rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had kept it close, making life awkward for Buatsi, who utilized a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance wore thin because of frequent holding, with Parker going down multiple occasions during grappling.
The underdog closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the presence of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Homage Motivates Local Rivalry Fight
In the secondary fight, Arthur beat Bradley Rea by split-decision in a excellent local rivalry battle to capture the continental championship.
The stadium became quiet for a extremely emotional homage prior to the bout as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the premier televised boxing event in the city since the passing of Hatton. As the concluding sound faded, the stillness became a chant of "there's only one Ricky Hatton".
The competition during the bout matched the emotion. Arthur was sent to the canvas by a left hook directly to the jaw in the initial stage, standing uncertainly to his position on the count of eight.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in competitive blue - was damaged early, heavy swelling appearing under his face as the pair exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with stinging uppercuts as the intensity rarely dropped over the full distance.
The victor barely secured the verdict with official scores of 114-114, 115-113 and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration Hatton stood for.
