British light-heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a split decision in a tight 10-round bout at the Co-op Live Arena.
But the challenger had his moments, delivering effective clean blows in a match where the techniques never quite clicked, with constant grabbing spoiling the action.
The scoring judges judged it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They win," the victor commented in the arena as he was faced negative reactions from the audience.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Some ringside observers felt Parker, thirty-one, deserved the decision but the Derbyshire fighter suffered the second loss of his 28-bout professional journey.
Buatsi Secures Win in Uneventful Encounter
The fighter's advancement has slowed in recent years through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to achieve expectations - possibly in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers willing to overcommit in a tentative initial 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 fight at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for the favorite, who utilized a solid defense to edge the better periods.
The crowd's patience decreased during regular grabbing, with Parker falling to the floor several times during clinches.
Parker ended stronger, but several stanzas were challenging to assess. Nevertheless, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just one round.
The victor advances, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Homage Fuels All-Manchester Contest
In the supporting bout, Arthur beat Rea by divided decision in a terrific all-Manchester fight to capture the continental title.
The stadium fell silent for a deeply poignant homage before the fight as ten bells sounded in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the city since Hatton's death. As the final chime disappeared, the quiet gave way to a shout of "there's just one Ricky Hatton".
The fighting during the bout reflected the feeling. Arthur was knocked down by a significant blow flush on the chin in the early round, standing uncertainly to his footing on the referee's count.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was injured soon, noticeable damage appearing under his eye as the duo traded punishing blows.
Rea, 27, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity hardly diminished over 12 rounds.
Arthur narrowly won the decision with scoring tallies of even score, 115-113 and clearer margin, but each competitor were persistent and full of heart, everything their hero Hatton embodied.
