UK light-heavyweight Buatsi secured a victory yet underwhelming start to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a tight ten-round contest at the boxing arena.
But the challenger found success, connecting with powerful single shots in a fight where the techniques failed to mesh, with constant grabbing spoiling the action.
The officials had it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my finest display but how do champions respond? They win," the victor said in the ring as he was greeted with boos from the spectators.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th career victory.
Several boxing experts felt the challenger, 31, merited the decision but the contender experienced the second loss of his 28-match career.
The Champion Earns Triumph in Dull Affair
Buatsi's progress has stalled in the past few years through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of UK boxing, he now stands trying to achieve expectations - maybe in what seems like a last chance - under recent support.
He started carefully, with both competitors willing to be aggressive in a tentative initial rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second bout at light-heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who utilized a protective stance to edge the more effective stanzas.
The spectators' acceptance decreased during frequent holding, with Parker slipping to the canvas several times during close exchanges.
Parker finished the stronger, but multiple periods were difficult to score. However, previous titleholder Carl Frampton - working with Dazn - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the likes of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Hatton Homage Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a terrific all-Manchester battle to secure the European light heavyweight championship.
The stadium fell silent for a deeply poignant tribute prior to the bout as ten bells rang in honor of the city's native Ricky Hatton, who passed away 46 years old in recently.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the last bell disappeared, the silence gave way to a shout of "only one Hatton".
The competition inside the ropes matched the feeling. Arthur was sent to the canvas by a significant blow flush on the face in the second round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. Across the ring, the opponent - in rival City blue - was damaged early, heavy swelling forming under his face as the pair landed hard punches.
The challenger, twenty-seven, landed power punches but the champion, 34, responded in kind with powerful upward punches as the pace seldom decreased over twelve rounds.
The victor barely secured the verdict with judges scorecards of even score, narrow lead and 115-112, but each competitor were relentless and courageous, all the qualities their idol Hatton represented.
