UK light heavyweight Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But Parker had his moments, connecting with powerful individual punches in a contest where the styles never quite clicked, with excessive holding marring the contest.
Two judges judged it 96-94 for to the winner, with the final judge a even score.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the ringside as he was met by disapproval from the spectators.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Various analysts felt the challenger, thirty-one, deserved the win but the contender endured the second defeat of his 28-match professional journey.
The Champion Secures Victory in Dull Affair
Buatsi's progress has plateaued in the past few years through promotional disputes and long spells of inactivity.
Earlier forecast as the future of British boxing, he now is positioned trying to fulfil that early promise - maybe in what feels like a last chance - under fresh management.
He began cautiously, with both competitors ready to be aggressive in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after damaging his hand mid-fight, was making just his second fight at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who operated with a tight guard to narrowly win the better periods.
The spectators' acceptance diminished during frequent holding, with the challenger falling to the floor multiple occasions during clinches.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Motivates Manchester Derby Fight
In the supporting bout, Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester fight to win the European light heavyweight championship.
The stadium became quiet for a extremely emotional tribute ahead of the contest as a bell ceremony tolled in remembrance of the city's native Ricky Hatton, who succumbed at age 46 in September.
It was the first major televised fight night in the city since Hatton's passing. As the final chime ended, the quiet gave way to a roar of "only one Hatton".
The competition within the ring matched the sentiment. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the second round, rising shakily to his feet on the eight count.
But the traditional red shorts of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was damaged soon, noticeable damage appearing under his orbital area as the fighters exchanged punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over twelve rounds.
The victor barely secured the verdict with scoring tallies of even score, close margin and 115-112, but each competitor were determined and courageous, everything their inspiration the legend embodied.
