British light heavyweight Buatsi earned a win yet underwhelming start to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a close 10-round fight at the boxing arena.
But Parker found success, delivering effective individual punches in a fight where the styles failed to mesh, with frequent clinching spoiling the fight.
The scoring judges judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my finest display but what defines champions? They win," the victor said in the ring as he was faced boos from the spectators.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in February - to earn a 20th pro success.
Several boxing experts believed Parker, 31, deserved the win but the British boxer endured the second setback of his 28-fight career.
The Champion Claims Triumph in Uneventful Encounter
His career development has stalled in the past few years through promotional disputes and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to achieve expectations - maybe in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers prepared to be aggressive in a cagey opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second fight at light-heavyweight.
By the halfway stage, Parker had kept it close, creating difficulties for the favorite, who operated with a tight guard to barely take the better periods.
The crowd's patience decreased amid frequent holding, with Parker slipping to the canvas various instances during clinches.
Parker finished the stronger, but multiple periods were difficult to score. Although, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
The victor moves on, but with the likes of power puncher Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Memorial Fuels Local Rivalry Contest
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester battle to secure the continental championship.
The arena grew hushed for a deeply poignant tribute ahead of the contest as a bell ceremony tolled in honor of local hero Hatton, who died aged 46 in last month.
It was the first major televised match card in the location since Hatton's passing. As the concluding sound faded, the quiet transitioned to a shout of "there's only one Ricky Hatton".
The action within the ring equaled the feeling. Arthur was knocked down by a powerful punch squarely on the jaw in the early round, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon came forward again. From the other corner, Rea - in opposing blue - was marked up early, heavy swelling forming under his eye as the pair landed punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the action hardly diminished over the full distance.
The victor barely secured the result with judges scorecards of even score, narrow lead and wider gap, but both fighters were relentless and brave, all the qualities their hero the legend stood for.
