UK light heavyweight Buatsi earned a win yet underwhelming debut to his career under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a close ten-round fight at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a fight where the styles never quite clicked, with constant grabbing marring the contest.
The officials scored it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my finest display but what defines champions? They prevail," Buatsi commented in the ringside as he was faced disapproval from the spectators.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to earn a 20th pro success.
Several boxing experts thought the challenger, 31, deserved the victory but the contender suffered the second defeat of his 28-match professional journey.
The Champion Claims Win in Dull Match
Buatsi's progress has stalled in recent years through management issues and long spells of inactivity.
Once tipped as the next star of UK boxing, he now stands trying to realize his potential - possibly in what feels like a final roll of the dice - under fresh management.
He began cautiously, with both competitors prepared to be aggressive in a calculated initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was participating in his second fight at light heavyweight.
By the middle rounds, Parker had kept it close, making life awkward for Buatsi, who operated with a solid defense to narrowly win the better rounds.
The crowd's patience decreased during constant clinching, with the challenger going down multiple occasions during clinches.
The underdog closed well, but multiple periods were hard to judge. However, ex-champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Tribute Motivates Local Rivalry Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester contest to capture the European light-heavyweight championship.
The arena fell silent for a deeply poignant homage prior to the bout as a bell ceremony rang in honor of the city's native Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the last bell ended, the silence gave way to a shout of "there's just one Ricky Hatton".
The competition inside the ropes matched the feeling. Arthur was sent to the canvas by a left hook squarely on the jaw in the early round, standing uncertainly to his position on the eight count.
But the red-colored attire of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was damaged quickly, noticeable damage developing under his eye as the duo landed powerful shots.
Rea, 27, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the pace rarely dropped over 12 rounds.
The victor edged the result with official scores of 114-114, 115-113 and clearer margin, but both fighters were relentless and courageous, exactly what their hero Hatton stood for.
