UK light-heavyweight Buatsi earned a win yet unimpressive beginning to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight ten-round fight at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a match where the approaches didn't complement each other, with constant grabbing spoiling the contest.
Two judges had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They win," Buatsi stated in the ring as he was met by negative reactions from the spectators.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Various analysts thought the challenger, 31, should have been awarded the victory but the contender endured the second setback of his 28-bout career.
Buatsi Claims Win in Slow Match
His career development has stalled in recent times through promotional disputes and considerable time of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - possibly in what seems like a last chance - under recent support.
He began cautiously, with neither fighter prepared to overcommit in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a solid defense to edge the better periods.
The audience's tolerance diminished because of regular grabbing, with the challenger falling to the floor multiple occasions during grappling.
Parker finished the stronger, but multiple periods were challenging to assess. Although, ex-champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, giving Buatsi just a single round.
Buatsi moves on, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Motivates All-Manchester Contest
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester battle to secure the European light-heavyweight belt.
The arena fell silent for a deeply poignant homage prior to the bout as a bell ceremony tolled in honor of Manchester's own Hatton, who passed away 46 years old in September.
It was the premier televised boxing event in the urban center since Hatton's passing. As the final chime ended, the stillness transitioned to a shout of "there's only one Hatton".
The action within the ring matched the feeling. Arthur was knocked down by a significant blow directly to the face in the initial stage, rising shakily to his position on the count of eight.
But the traditional red equipment of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was injured early, noticeable damage developing under his face as the duo exchanged punishing blows.
The challenger, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the action rarely dropped over 12 rounds.
Arthur barely secured the verdict with scoring tallies of draw, 115-113 and clearer margin, but both fighters were persistent and brave, all the qualities their idol Hatton embodied.
