British light-heavyweight Buatsi earned a win yet disappointing debut to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a close ten-round fight at the Manchester venue.
But the challenger found success, landing some telling single shots in a fight where the styles never quite clicked, with excessive holding spoiling the contest.
Two judges judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my best performance but what do champions do? They win," the victor said in the ring as he was faced boos from the crowd.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Various analysts believed Parker, thirty-one, deserved the victory but the Derbyshire fighter experienced the second defeat of his 28-fight career.
Buatsi Claims Win in Slow Affair
His career development has plateaued in recent years through management issues and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to realize his potential - possibly in what seems like a ultimate opportunity - under recent support.
He opened tentatively, with both competitors willing to take risks in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after damaging his hand mid-fight, was competing in only his second fight at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who operated with a tight guard to edge the more effective stanzas.
The audience's tolerance diminished amid constant clinching, with Parker falling to the floor multiple occasions during grappling.
The underdog closed well, but many rounds were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor progresses, but with the caliber of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a terrific all-Manchester fight to secure the European light-heavyweight title.
The arena fell silent for a profoundly moving memorial ahead of the contest as 10 bells tolled in remembrance of the city's native Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the location since Hatton's death. As the final chime faded, the silence gave way to a chant of "there's just one Ricky Hatton".
The action inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a left hook flush on the jaw in the second round, rising shakily to his footing on the eight count.
But the red-colored shorts of the fighter soon came forward again. From the other corner, Rea - in rival City blue - was injured quickly, heavy swelling appearing under his face as the pair exchanged punishing blows.
The challenger, 27, connected with strong blows but the champion, thirty-four, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
The victor barely secured the verdict with official scores of even score, close margin and clearer margin, but the two athletes were relentless and courageous, exactly what their idol Hatton stood for.
