British light-heavyweight Buatsi made a winning yet unimpressive start to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a close ten-round contest at the Manchester venue.
But the challenger had his moments, connecting with powerful single shots in a contest where the approaches never quite clicked, with excessive holding marring the contest.
The officials had it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best showing but what defines champions? They win," Buatsi said in the arena as he was met by disapproval from the crowd.
The British fighter returned to winning ways after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th pro success.
Several boxing experts felt Parker, thirty-one, merited the decision but the Derbyshire fighter endured the second defeat of his 28-bout career.
The Champion Claims Win in Uneventful Encounter
Buatsi's progress has stalled in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the future of British boxing, he now stands trying to achieve expectations - maybe in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter willing to be aggressive in a cagey opening few rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was making just his second fight at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for the favorite, who utilized a protective stance to barely take the better stanzas.
The spectators' acceptance diminished because of frequent holding, with the challenger falling to the floor various instances during grappling.
Parker finished the stronger, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Russian champion Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Tribute Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur beat Rea by divided decision in a excellent local rivalry contest to capture the European light-heavyweight title.
The stadium fell silent for a deeply poignant memorial ahead of the contest as a bell ceremony sounded in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the first major televised boxing event in the city since Hatton's death. As the concluding sound ended, the quiet gave way to a roar of "there's just one Hatton".
The fighting inside the ropes reflected the emotion. Arthur was floored by a powerful punch squarely on the face in the early round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red shorts of Arthur soon came forward again. Across the ring, Rea - in opposing blue - was damaged early, significant bruising appearing under his orbital area as the fighters traded hard punches.
The challenger, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over the full distance.
The victor barely secured the result with judges scorecards of even score, close margin and clearer margin, but each competitor were relentless and courageous, all the qualities their inspiration Hatton embodied.
