UK light heavyweight Buatsi secured a victory yet disappointing start to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a tight ten-round contest at the boxing arena.
But the challenger had his moments, delivering effective clean blows in a contest where the styles failed to mesh, with constant grabbing marring the fight.
The officials judged it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but what do champions do? They succeed," the victor stated in the arena as he was faced disapproval from the audience.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to secure a 20th pro success.
Several boxing experts thought Parker, 31, deserved the decision but the contender suffered the second loss of his 28-bout career.
The Champion Claims Win in Uneventful Encounter
The fighter's advancement has slowed in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the next star of British boxing, he now finds himself trying to realize his potential - perhaps in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers willing to take risks in a calculated initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand in the contest, was participating in his second bout at the higher weight class.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who utilized a protective stance to barely take the more effective stanzas.
The spectators' acceptance decreased during frequent holding, with Parker falling to the floor multiple occasions during clinches.
The underdog ended stronger, but many rounds were difficult to score. Although, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Fuels Manchester Derby Fight
In the co-main event, Lyndon Arthur beat Rea by divided decision in a excellent all-Manchester battle to capture the continental title.
The stadium fell silent for a profoundly moving homage before the fight as a bell ceremony rang in memory of Manchester's own Hatton, who succumbed aged 46 in recently.
It was the premier televised match card in the city since the passing of Hatton. As the concluding sound disappeared, the quiet became a shout of "only one Hatton".
The competition within the ring matched the feeling. Arthur was sent to the canvas by a powerful punch squarely on the jaw in the initial stage, rising shakily to his footing on the eight count.
But the Manchester United-red attire of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was injured soon, noticeable damage appearing under his eye as the duo traded powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the action rarely dropped over 12 rounds.
The victor barely secured the result with scoring tallies of even score, close margin and wider gap, but both fighters were persistent and brave, all the qualities their inspiration the legend embodied.
