UK light-heavyweight Buatsi secured a victory yet underwhelming beginning to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But the challenger had his moments, delivering effective individual punches in a contest where the techniques never quite clicked, with frequent clinching spoiling the action.
Two judges scored it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my finest display but what do champions do? They succeed," the victor said in the ringside as he was faced negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers believed the challenger, thirty-one, deserved the decision but the Derbyshire fighter endured the second setback of his 28-fight professional journey.
Buatsi Secures Victory in Slow Match
Buatsi's progress has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a last chance - under new promotional backing.
He began cautiously, with both competitors ready to take risks in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who utilized a tight guard to edge the more effective stanzas.
The spectators' acceptance decreased amid frequent holding, with Parker slipping to the canvas multiple occasions during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Nevertheless, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - based on this performance - still seems difficult.
Hatton Tribute Fuels All-Manchester Contest
In the secondary fight, Arthur beat Bradley Rea by divided decision in a outstanding local rivalry fight to secure the continental belt.
The arena grew hushed for a deeply poignant memorial prior to the bout as a bell ceremony tolled in memory of the city's native Ricky Hatton, who died 46 years old in September.
It was the first major televised match card in the urban center since the passing of Hatton. As the last bell ended, the quiet became a roar of "there's only one Hatton".
The action within the ring equaled the feeling. Arthur was floored by a powerful punch squarely on the face in the second round, rising shakily to his position on the count of eight.
But the red-colored attire of Arthur soon advanced again. Across the ring, Rea - in opposing blue - was marked up early, heavy swelling forming under his eye as the pair exchanged punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the action rarely dropped over twelve rounds.
The victor barely secured the verdict with scoring tallies of 114-114, 115-113 and clearer margin, but the two athletes were persistent and courageous, all the qualities their inspiration Hatton stood for.
