British light heavyweight Buatsi made a winning yet underwhelming debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker had his moments, connecting with powerful individual punches in a fight where the techniques failed to mesh, with excessive holding marring the fight.
The officials judged it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my greatest display but what do champions do? They win," Buatsi stated in the arena as he was met by negative reactions from the spectators.
The British fighter got back to winning after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th career victory.
Several boxing experts thought Parker, thirty-one, should have been awarded the win but the British boxer experienced the second defeat of his 28-fight professional journey.
The Champion Secures Win in Dull Match
The fighter's advancement has slowed in recent times through contract problems and considerable time of inactivity.
Earlier forecast as the future of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors prepared to take risks in a calculated initial rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who worked behind a tight guard to edge the better periods.
The audience's tolerance diminished amid frequent holding, with Parker slipping to the canvas several times during close exchanges.
Parker closed well, but many rounds were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Hatton Homage Inspires Manchester Derby Contest
In the supporting bout, Lyndon Arthur overcame Rea by divided decision in a terrific all-Manchester contest to win the European light heavyweight championship.
The arena fell silent for a extremely emotional homage prior to the bout as ten bells rang in honor of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell faded, the stillness transitioned to a roar of "there's just one Ricky Hatton".
The competition during the bout reflected the emotion. The eventual winner was floored by a left hook squarely on the face in the initial stage, getting up unsteadily to his feet on the count of eight.
But the red-colored attire of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was injured early, noticeable damage developing under his face as the fighters traded hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity rarely dropped over 12 rounds.
The victor edged the verdict with judges scorecards of 114-114, narrow lead and clearer margin, but both fighters were persistent and brave, all the qualities their idol Hatton stood for.
