British light-heavyweight Buatsi earned a win yet disappointing beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a split decision in a competitive ten-round fight at the Manchester venue.
But Parker found success, delivering effective clean blows in a fight where the styles didn't complement each other, with constant grabbing marring the action.
The scoring judges judged it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my greatest display but what do champions do? They win," the victor commented in the arena as he was faced disapproval from the crowd.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in February - to claim a twentieth professional win.
Various analysts thought Parker, thirty-one, deserved the win but the British boxer experienced the second loss of his 28-fight career.
Buatsi Claims Triumph in Slow Encounter
Buatsi's progress has plateaued in the past few years through management issues and considerable time of inactivity.
Previously predicted as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter willing to be aggressive in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was participating in his second fight at light-heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for Buatsi, who operated with a protective stance to barely take the cleaner rounds.
The audience's tolerance wore thin during constant clinching, with Parker going down several times during clinches.
Parker closed well, but multiple periods were difficult to score. Although, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific local rivalry fight to capture the European light-heavyweight title.
The arena grew hushed for a profoundly moving memorial prior to the bout as a bell ceremony tolled in memory of local hero Ricky Hatton, who succumbed at age 46 in last month.
It was the premier televised fight night in the location since the passing of Hatton. As the concluding sound disappeared, the quiet transitioned to a roar of "there's only one Ricky Hatton".
The competition during the bout reflected the emotion. The eventual winner was knocked down by a significant blow squarely on the face in the initial stage, getting up unsteadily to his feet on the count of eight.
But the red-colored shorts of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was damaged quickly, noticeable damage forming under his eye as the fighters exchanged punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with stinging uppercuts as the action seldom decreased over the full distance.
The victor narrowly won the result with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were determined and courageous, everything their inspiration the legend embodied.
