British light heavyweight Buatsi secured a victory yet underwhelming start to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a split decision in a tight 10-round bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a match where the styles didn't complement each other, with constant grabbing spoiling the contest.
Two judges scored it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but how do champions respond? They prevail," the victor said in the ringside as he was faced boos from the audience.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to secure a 20th career victory.
Several boxing experts thought Parker, 31, merited the win but the contender endured the second defeat of his 28-bout career.
The Champion Secures Triumph in Dull Match
Buatsi's progress has stalled in recent times through contract problems and extended periods of lack of fights.
Once tipped as the future of British boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under fresh management.
He began cautiously, with the two boxers prepared to take risks in a cagey early stages.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second fight at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for the favorite, who worked behind a solid defense to edge the cleaner periods.
The crowd's patience diminished because of frequent holding, with Parker going down multiple occasions during close exchanges.
The underdog finished the stronger, but several stanzas were challenging to assess. However, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Memorial Motivates Manchester Derby Battle
In the secondary fight, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent local rivalry fight to secure the continental belt.
The venue became quiet for a deeply poignant homage ahead of the contest as a bell ceremony rang in memory of the city's native Hatton, who died aged 46 in last month.
It was the premier televised boxing event in the city since the passing of Hatton. As the final chime disappeared, the stillness transitioned to a roar of "there's just one Hatton".
The fighting inside the ropes matched the emotion. Arthur was floored by a left hook directly to the jaw in the second round, standing uncertainly to his position on the referee's count.
But the traditional red attire of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was damaged quickly, heavy swelling forming under his orbital area as the fighters exchanged powerful shots.
The challenger, 27, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the pace rarely dropped over 12 rounds.
Arthur narrowly won the decision with official scores of draw, close margin and 115-112, but both fighters were persistent and courageous, all the qualities their hero the legend represented.
