British light heavyweight Buatsi earned a win yet disappointing start to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a tight ten-round contest at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling single shots in a contest where the styles didn't complement each other, with constant grabbing marring the action.
The officials scored it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but how do champions respond? They succeed," Buatsi commented in the ring as he was faced boos from the spectators.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in February - to claim a 20th pro success.
Several boxing experts felt the challenger, 31, deserved the victory but the British boxer suffered the second setback of his 28-match career.
Buatsi Claims Win in Dull Affair
His career development has stalled in the past few years through management issues and extended periods of lack of fights.
Previously predicted as the future of UK boxing, he now finds himself trying to realize his potential - maybe in what appears to be a last chance - under fresh management.
He opened tentatively, with both competitors prepared to take risks in a cagey early stages.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was making just his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a protective stance to narrowly win the more effective stanzas.
The crowd's patience decreased because of frequent holding, with Parker falling to the floor several times during grappling.
The underdog finished the stronger, but multiple periods were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the caliber of heavy hitter David Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding local rivalry battle to secure the continental title.
The venue became quiet for a profoundly moving memorial prior to the bout as ten bells rang in memory of local hero Hatton, who succumbed at age 46 in last month.
It was the first major televised match card in the location since Hatton's death. As the last bell ended, the quiet transitioned to a chant of "there's just one Hatton".
The competition during the bout reflected the sentiment. Arthur was floored by a powerful punch squarely on the face in the second round, standing uncertainly to his position on the referee's count.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, Rea - in competitive blue - was damaged quickly, noticeable damage developing under his face as the pair traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the pace seldom decreased over twelve rounds.
The victor barely secured the verdict with scoring tallies of 114-114, narrow lead and 115-112, but the two athletes were determined and courageous, everything their idol Hatton represented.
