UK light heavyweight Buatsi secured a victory yet underwhelming debut to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a close ten-round bout at the boxing arena.
But Parker had his moments, landing some telling individual punches in a contest where the styles didn't complement each other, with frequent clinching marring the action.
Two judges judged it 96-94 for to the winner, with the third a 95-95.
"It wasn't my finest performance but what defines champions? They succeed," the victor commented in the arena as he was met by disapproval from the crowd.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, merited the victory but the British boxer suffered the second defeat of his 28-match professional journey.
Buatsi Claims Triumph in Dull Match
The fighter's advancement has stalled in recent years through management issues and extended periods of inactivity.
Previously predicted as the future of British boxing, he now stands trying to realize his potential - possibly in what appears to be a final roll of the dice - under fresh management.
He opened tentatively, with both competitors ready to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in 2022 after breaking his hand during the bout, was participating in his second appearance at the higher weight class.
By the middle rounds, Parker had stayed in contention, making life awkward for Buatsi, who utilized a solid defense to edge the cleaner rounds.
The crowd's patience wore thin because of regular grabbing, with the challenger going down various instances during close exchanges.
Parker ended stronger, but many rounds were challenging to assess. Nevertheless, ex-champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor progresses, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the co-main event, Arthur defeated Bradley Rea by close verdict in a outstanding Manchester vs Manchester contest to secure the continental championship.
The arena fell silent for a extremely emotional memorial before the fight as ten bells tolled in memory of the city's native Ricky Hatton, who died aged 46 in last month.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell disappeared, the quiet gave way to a roar of "there's just one Hatton".
The fighting inside the ropes matched the emotion. Arthur was sent to the canvas by a left hook squarely on the face in the second round, getting up unsteadily to his position on the eight count.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was injured soon, heavy swelling appearing under his orbital area as the duo exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with powerful upward punches as the action seldom decreased over the full distance.
The victor edged the decision with judges scorecards of draw, narrow lead and 115-112, but each competitor were persistent and brave, everything their hero Hatton embodied.
