UK light heavyweight Buatsi secured a victory yet disappointing beginning to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a tight ten-round contest at the Manchester venue.
But Parker found success, landing some telling clean blows in a fight where the styles failed to mesh, with excessive holding spoiling the action.
The officials had it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my finest display but how do champions respond? They win," Buatsi commented in the ringside as he was greeted with boos from the spectators.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to earn a 20th pro success.
Several boxing experts believed Parker, thirty-one, merited the decision but the contender endured the second setback of his 28-fight career.
The Champion Earns Win in Dull Encounter
Buatsi's progress has plateaued in the past few years through contract problems and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to achieve expectations - maybe in what seems like a final roll of the dice - under fresh management.
He started carefully, with both competitors prepared to be aggressive in a tentative early stages.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who worked behind a protective stance to narrowly win the more effective stanzas.
The audience's tolerance decreased during frequent holding, with the challenger falling to the floor multiple occasions during grappling.
Parker ended stronger, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, awarding Buatsi just a single round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Hatton Memorial Fuels All-Manchester Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a excellent local rivalry contest to secure the European light-heavyweight title.
The arena became quiet for a deeply poignant memorial prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who passed away aged 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the final chime faded, the quiet gave way to a chant of "there's only one Ricky Hatton".
The action within the ring equaled the feeling. The eventual winner was knocked down by a powerful punch directly to the chin in the initial stage, rising shakily to his footing on the count of eight.
But the traditional red shorts of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was marked up quickly, noticeable damage forming under his face as the pair traded hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over 12 rounds.
The victor edged the decision with judges scorecards of even score, close margin and 115-112, but both fighters were relentless and courageous, exactly what their inspiration the legend embodied.
