UK light heavyweight Buatsi secured a victory yet unimpressive start to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a majority decision in a competitive ten-round contest at the Manchester venue.
But Parker had his moments, landing some telling single shots in a fight where the techniques didn't complement each other, with excessive holding disrupting the contest.
The scoring judges scored it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest display but how do champions respond? They succeed," the victor stated in the arena as he was greeted with negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to claim a 20th pro success.
Some ringside observers thought the challenger, 31, deserved the victory but the Derbyshire fighter suffered the second defeat of his 28-bout professional journey.
Buatsi Earns Win in Slow Encounter
The fighter's advancement has slowed in the past few years through contract problems and extended periods of lack of fights.
Previously predicted as the next star of UK boxing, he now is positioned trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter ready to overcommit in a cagey early stages.
The challenger, whose sole prior loss came at super middleweight against John Ryder in 2022 after breaking his hand mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who utilized a tight guard to narrowly win the more effective rounds.
The audience's tolerance diminished because of regular grabbing, with Parker falling to the floor multiple occasions during grappling.
Parker ended stronger, but many rounds were difficult to score. However, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the caliber of heavy hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Memorial Fuels Manchester Derby Battle
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a excellent all-Manchester contest to secure the European light heavyweight championship.
The venue became quiet for a deeply poignant memorial before the fight as 10 bells tolled in honor of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the premier televised match card in the urban center since Hatton's passing. As the final chime ended, the quiet gave way to a chant of "only one Ricky Hatton".
The competition inside the ropes matched the feeling. The eventual winner was floored by a left hook squarely on the jaw in the second round, rising shakily to his feet on the count of eight.
But the Manchester United-red attire of Arthur soon advanced again. Across the ring, Rea - in competitive blue - was injured early, heavy swelling developing under his eye as the pair traded powerful shots.
The challenger, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over the full distance.
Arthur barely secured the decision with scoring tallies of even score, close margin and 115-112, but each competitor were relentless and full of heart, exactly what their inspiration Hatton stood for.
