UK light heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a majority decision in a tight 10-round bout at the boxing arena.
But Parker had his moments, connecting with powerful single shots in a contest where the approaches never quite clicked, with constant grabbing spoiling the fight.
Two judges had it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They prevail," Buatsi said in the arena as he was met by negative reactions from the audience.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Several boxing experts felt the challenger, thirty-one, deserved the victory but the contender endured the second setback of his 28-bout career.
Buatsi Earns Triumph in Slow Match
His career development has plateaued in recent times through management issues and extended periods of inactivity.
Earlier forecast as the rising talent of UK boxing, he now is positioned trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under recent support.
He opened tentatively, with the two boxers prepared to be aggressive in a calculated early stages.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who operated with a tight guard to narrowly win the cleaner rounds.
The crowd's patience decreased during frequent holding, with Parker slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but multiple periods were challenging to assess. Although, ex-champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just only one stanza.
The victor advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - on this evidence - still seems difficult.
Hatton Tribute Motivates Manchester Derby Fight
In the supporting bout, Lyndon Arthur defeated Rea by divided decision in a outstanding Manchester vs Manchester fight to win the continental belt.
The stadium fell silent for a extremely emotional tribute ahead of the contest as 10 bells sounded in remembrance of the city's native Ricky Hatton, who passed away 46 years old in last month.
It was the first major televised match card in the city since Hatton's passing. As the last bell faded, the quiet became a chant of "there's just one Ricky Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the initial stage, rising shakily to his footing on the count of eight.
But the red-colored shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the duo exchanged hard punches.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over the full distance.
Arthur narrowly won the decision with official scores of draw, close margin and wider gap, but each competitor were relentless and brave, everything their idol Hatton embodied.
