UK light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a split decision in a tight 10-round contest at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful individual punches in a fight where the approaches failed to mesh, with frequent clinching disrupting the action.
The officials scored it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my best performance but how do champions respond? They prevail," Buatsi commented in the ringside as he was greeted with negative reactions from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to secure a 20th pro success.
Some ringside observers believed Parker, 31, merited the decision but the British boxer endured the second setback of his 28-match career.
Buatsi Secures Triumph in Uneventful Encounter
The fighter's advancement has plateaued in recent years through promotional disputes and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with the two boxers willing to take risks in a calculated opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for Buatsi, who operated with a tight guard to edge the cleaner rounds.
The spectators' acceptance diminished amid frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were hard to judge. However, previous titleholder the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the co-main event, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent all-Manchester fight to secure the European light-heavyweight title.
The arena fell silent for a profoundly moving tribute ahead of the contest as ten bells tolled in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the final chime disappeared, the quiet transitioned to a shout of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the emotion. Arthur was knocked down by a left hook squarely on the chin in the second round, standing uncertainly to his feet on the referee's count.
But the traditional red attire of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was injured soon, significant bruising forming under his eye as the pair traded punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with stinging uppercuts as the pace rarely dropped over twelve rounds.
Arthur narrowly won the decision with official scores of draw, close margin and wider gap, but each competitor were determined and courageous, all the qualities their inspiration the legend stood for.
