British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a majority decision in a close ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, landing some telling single shots in a match where the styles never quite clicked, with constant grabbing disrupting the contest.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They succeed," Buatsi stated in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers thought Parker, 31, deserved the victory but the Derbyshire fighter experienced the second defeat of his 28-bout professional journey.
The Champion Earns Triumph in Uneventful Match
The fighter's advancement has slowed in recent times through contract problems and considerable time of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers prepared to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second fight at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to edge the better periods.
The crowd's patience wore thin during frequent holding, with Parker going down various instances during clinches.
The underdog finished the stronger, but multiple periods were difficult to score. Although, ex-champion the boxing analyst - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just one round.
The victor progresses, but with the presence of hard hitter Benavidez, and Russian champion Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Hatton Tribute Motivates Manchester Derby Fight
In the supporting bout, Arthur overcame Rea by close verdict in a excellent Manchester vs Manchester contest to capture the continental championship.
The arena grew hushed for a extremely emotional tribute before the fight as a bell ceremony rang in memory of local hero Hatton, who passed away at age 46 in September.
It was the initial significant broadcast match card in the urban center since the passing of Hatton. As the last bell ended, the quiet transitioned to a roar of "there's only one Ricky Hatton".
The competition inside the ropes reflected the sentiment. Arthur was sent to the canvas by a left hook flush on the chin in the second round, rising shakily to his feet on the count of eight.
But the traditional red equipment of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his face as the duo traded punishing blows.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the pace hardly diminished over twelve rounds.
Arthur barely secured the decision with official scores of 114-114, 115-113 and wider gap, but both fighters were persistent and full of heart, everything their inspiration the legend stood for.
