UK light-heavyweight Buatsi secured a victory yet underwhelming beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a split decision in a competitive 10-round fight at the Manchester venue.
But Parker had his moments, delivering effective clean blows in a contest where the styles failed to mesh, with constant grabbing marring the fight.
The scoring judges scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest showing but what defines champions? They win," Buatsi commented in the ringside as he was greeted with negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to earn a 20th career victory.
Some ringside observers felt the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter experienced the second setback of his 28-fight career.
The Champion Secures Triumph in Slow Affair
The fighter's advancement has slowed in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to achieve expectations - maybe in what feels like a final roll of the dice - under fresh management.
He began cautiously, with both competitors ready to be aggressive in a tentative initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was making just his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who operated with a solid defense to narrowly win the better rounds.
The spectators' acceptance wore thin during regular grabbing, with the challenger falling to the floor multiple occasions during clinches.
Parker closed well, but multiple periods were hard to judge. Although, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - judging by this showing - still appears challenging.
Hatton Homage Fuels All-Manchester Contest
In the supporting bout, Arthur beat Bradley Rea by divided decision in a terrific local rivalry battle to win the European light-heavyweight championship.
The arena became quiet for a deeply poignant memorial before the fight as ten bells tolled in memory of Manchester's own Ricky Hatton, who succumbed aged 46 in recently.
It was the first major televised match card in the urban center since Hatton's passing. As the concluding sound disappeared, the silence became a roar of "only one Hatton".
The action during the bout reflected the feeling. The eventual winner was sent to the canvas by a significant blow squarely on the chin in the early round, getting up unsteadily to his feet on the eight count.
But the traditional red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up quickly, significant bruising appearing under his orbital area as the pair exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with stinging uppercuts as the action rarely dropped over 12 rounds.
The victor narrowly won the result with official scores of even score, close margin and clearer margin, but both fighters were determined and full of heart, all the qualities their hero Hatton stood for.
