British light-heavyweight Buatsi made a winning yet unimpressive start to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a tight ten-round contest at the Co-op Live Arena.
But the challenger had his moments, delivering effective single shots in a contest where the styles never quite clicked, with excessive holding spoiling the fight.
Two judges had it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my finest display but what do champions do? They win," the victor said in the arena as he was greeted with disapproval from the audience.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers thought Parker, 31, should have been awarded the victory but the Derbyshire fighter endured the second loss of his 28-match career.
Buatsi Secures Victory in Slow Affair
His career development has stalled in the past few years through contract problems and considerable time of lack of fights.
Previously predicted as the rising talent of the British fight scene, he now stands trying to achieve expectations - possibly in what appears to be a final roll of the dice - under fresh management.
He opened tentatively, with both competitors prepared to be aggressive in a cagey initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was making just his second bout at the higher weight class.
By the halfway stage, Parker had kept it close, causing problems for the favorite, who operated with a protective stance to narrowly win the better periods.
The audience's tolerance decreased because of regular grabbing, with Parker going down multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were difficult to score. Nevertheless, previous titleholder the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Memorial Fuels Manchester Derby Fight
In the supporting bout, Lyndon Arthur overcame Rea by divided decision in a excellent all-Manchester fight to win the European light heavyweight title.
The venue became quiet for a extremely emotional tribute before the fight as a bell ceremony tolled in honor of the city's native Ricky Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the concluding sound ended, the silence gave way to a chant of "only one Ricky Hatton".
The action during the bout reflected the emotion. The eventual winner was knocked down by a powerful punch squarely on the chin in the early round, rising shakily to his feet on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was marked up soon, noticeable damage developing under his face as the fighters exchanged hard punches.
Rea, 27, landed power punches but Arthur, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over the full distance.
Arthur edged the result with judges scorecards of 114-114, narrow lead and 115-112, but both fighters were relentless and full of heart, exactly what their hero Hatton embodied.
