UK light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a split decision in a competitive 10-round bout at the Co-op Live Arena.
But Parker had his moments, connecting with powerful individual punches in a match where the styles didn't complement each other, with frequent clinching disrupting the action.
The scoring judges scored it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest display but what do champions do? They prevail," the victor commented in the ringside as he was met by disapproval from the spectators.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to secure a 20th pro success.
Some ringside observers thought Parker, 31, merited the victory but the British boxer suffered the second setback of his 28-bout career.
Buatsi Claims Victory in Uneventful Affair
The fighter's advancement has slowed in recent years through contract problems and long spells of inactivity.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to realize his potential - perhaps in what feels like a last chance - under new promotional backing.
He opened tentatively, with the two boxers willing to take risks in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, was making just his second bout at the higher weight class.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who operated with a solid defense to edge the better rounds.
The audience's tolerance decreased because of regular grabbing, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. However, previous titleholder Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Fight
In the co-main event, Lyndon Arthur defeated Bradley Rea by close verdict in a terrific all-Manchester contest to win the continental title.
The arena fell silent for a deeply poignant memorial before the fight as a bell ceremony tolled in memory of the city's native Hatton, who succumbed 46 years old in September.
It was the premier televised match card in the urban center since Hatton's death. As the concluding sound ended, the silence gave way to a chant of "there's only one Hatton".
The action during the bout equaled the feeling. The eventual winner was sent to the canvas by a significant blow flush on the jaw in the early round, standing uncertainly to his position on the eight count.
But the traditional red equipment of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was marked up soon, heavy swelling forming under his eye as the fighters traded powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, responded in kind with effective uppercuts as the pace hardly diminished over the full distance.
The victor narrowly won the decision with official scores of even score, narrow lead and 115-112, but the two athletes were relentless and full of heart, all the qualities their hero Hatton embodied.
