British light heavyweight Buatsi made a winning yet unimpressive debut to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a split decision in a close 10-round contest at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a contest where the styles never quite clicked, with excessive holding spoiling the action.
The scoring judges judged it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my greatest performance but what defines champions? They succeed," Buatsi commented in the ringside as he was faced disapproval from the crowd.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to secure a twentieth professional win.
Several boxing experts believed the challenger, 31, deserved the victory but the Derbyshire fighter endured the second setback of his 28-fight professional journey.
The Champion Secures Win in Dull Encounter
Buatsi's progress has plateaued in the past few years through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now stands trying to fulfil that early promise - possibly in what seems like a last chance - under recent support.
He opened tentatively, with both competitors willing to take risks in a tentative initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second fight at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a tight guard to barely take the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with Parker going down multiple occasions during grappling.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor advances, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still seems difficult.
Hatton Memorial Inspires Local Rivalry Fight
In the co-main event, Arthur overcame Bradley Rea by divided decision in a outstanding local rivalry contest to win the European light heavyweight championship.
The arena grew hushed for a profoundly moving homage before the fight as 10 bells rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in September.
It was the first major televised boxing event in the city since the passing of Hatton. As the concluding sound ended, the quiet transitioned to a roar of "there's just one Ricky Hatton".
The fighting within the ring matched the sentiment. The eventual winner was sent to the canvas by a significant blow directly to the jaw in the initial stage, standing uncertainly to his footing on the eight count.
But the red-colored attire of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was damaged quickly, significant bruising appearing under his orbital area as the fighters traded hard punches.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with stinging uppercuts as the intensity hardly diminished over twelve rounds.
The victor edged the decision with judges scorecards of draw, narrow lead and 115-112, but both fighters were relentless and full of heart, everything their hero Hatton represented.
