UK light heavyweight Buatsi made a winning yet underwhelming debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a competitive ten-round bout at the boxing arena.
But Parker found success, delivering effective clean blows in a match where the approaches never quite clicked, with constant grabbing disrupting the fight.
Two judges had it 96-94 for to the winner, with the final judge a even score.
"It wasn't my best showing but what do champions do? They succeed," Buatsi said in the ring as he was greeted with disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with his previous opponent in February - to earn a 20th career victory.
Some ringside observers believed Parker, 31, deserved the win but the contender suffered the second defeat of his 28-bout professional journey.
Buatsi Secures Win in Slow Affair
The fighter's advancement has stalled in recent years through management issues and long spells of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors ready to take risks in a tentative opening few rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was competing in only his second fight at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to narrowly win the cleaner periods.
The spectators' acceptance decreased during constant clinching, with Parker slipping to the canvas various instances during clinches.
The underdog finished the stronger, but many rounds were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Hatton Memorial Inspires Manchester Derby Fight
In the supporting bout, Arthur beat Bradley Rea by split-decision in a excellent local rivalry battle to secure the European light heavyweight championship.
The venue became quiet for a deeply poignant memorial before the fight as a bell ceremony rang in honor of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the initial significant broadcast match card in the location since Hatton's passing. As the concluding sound ended, the silence gave way to a chant of "only one Hatton".
The competition within the ring matched the sentiment. The eventual winner was sent to the canvas by a left hook flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the traditional red shorts of the fighter soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with effective uppercuts as the action seldom decreased over twelve rounds.
Arthur narrowly won the result with official scores of even score, close margin and clearer margin, but each competitor were determined and full of heart, everything their idol Hatton represented.
