British light-heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a competitive ten-round fight at the boxing arena.
But Parker found success, delivering effective individual punches in a contest where the styles didn't complement each other, with frequent clinching disrupting the fight.
The officials scored it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my best performance but what defines champions? They succeed," Buatsi said in the ring as he was met by boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers believed Parker, 31, should have been awarded the decision but the contender suffered the second defeat of his 28-fight career.
Buatsi Earns Win in Dull Affair
Buatsi's progress has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now is positioned trying to realize his potential - possibly in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with neither fighter prepared to be aggressive in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second fight at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who operated with a tight guard to narrowly win the cleaner stanzas.
The spectators' acceptance wore thin during frequent holding, with Parker falling to the floor various instances during close exchanges.
The underdog closed well, but multiple periods were challenging to assess. However, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the supporting bout, Lyndon Arthur defeated Rea by split-decision in a excellent Manchester vs Manchester fight to capture the European light-heavyweight belt.
The stadium became quiet for a deeply poignant tribute ahead of the contest as 10 bells sounded in honor of the city's native Ricky Hatton, who passed away aged 46 in recently.
It was the premier televised boxing event in the urban center since Hatton's passing. As the final chime disappeared, the silence gave way to a shout of "there's only one Hatton".
The action inside the ropes matched the feeling. The eventual winner was knocked down by a significant blow squarely on the face in the early round, getting up unsteadily to his footing on the count of eight.
But the red-colored shorts of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was injured quickly, significant bruising developing under his orbital area as the duo landed punishing blows.
The challenger, 27, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor edged the verdict with scoring tallies of draw, close margin and wider gap, but both fighters were determined and full of heart, everything their hero Hatton embodied.
