UK light heavyweight Buatsi made a winning yet underwhelming beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a competitive ten-round fight at the Co-op Live Arena.
But the challenger had his moments, delivering effective single shots in a contest where the approaches didn't complement each other, with constant grabbing spoiling the action.
Two judges scored it 96-94 to Buatsi, with the third a even score.
"It wasn't my greatest showing but what defines champions? They succeed," the victor said in the arena as he was faced boos from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Various analysts thought the challenger, thirty-one, should have been awarded the decision but the Derbyshire fighter suffered the second defeat of his 28-match career.
Buatsi Claims Victory in Dull Match
His career development has plateaued in the past few years through promotional disputes and considerable time of inactivity.
Once tipped as the future of UK boxing, he now is positioned trying to achieve expectations - perhaps in what appears to be a last chance - under new promotional backing.
He opened tentatively, with the two boxers willing to take risks in a tentative opening few rounds.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who operated with a solid defense to narrowly win the more effective rounds.
The spectators' acceptance wore thin during regular grabbing, with the challenger going down several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. However, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
The victor advances, but with the likes of power puncher David Benavidez, and Russian champion Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Hatton Homage Motivates Manchester Derby Battle
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a terrific Manchester vs Manchester battle to secure the continental title.
The arena grew hushed for a deeply poignant homage prior to the bout as a bell ceremony sounded in honor of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the first major televised match card in the location since the passing of Hatton. As the last bell disappeared, the stillness transitioned to a shout of "there's just one Hatton".
The competition within the ring equaled the sentiment. The eventual winner was floored by a left hook squarely on the chin in the initial stage, rising shakily to his footing on the referee's count.
But the traditional red shorts of the fighter soon advanced again. From the other corner, Rea - in opposing blue - was marked up soon, noticeable damage developing under his eye as the duo exchanged hard punches.
Rea, 27, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the pace hardly diminished over twelve rounds.
Arthur barely secured the result with scoring tallies of even score, close margin and 115-112, but both fighters were persistent and brave, all the qualities their inspiration the legend represented.
