UK light-heavyweight Buatsi secured a victory yet disappointing start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a close ten-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful clean blows in a contest where the styles never quite clicked, with excessive holding spoiling the action.
Two judges judged it 96-94 to the winner, with the third a 95-95.
"It wasn't my greatest performance but what defines champions? They prevail," the victor commented in the ringside as he was met by negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the victory but the British boxer endured the second defeat of his 28-match professional journey.
Buatsi Secures Win in Uneventful Match
His career development has slowed in recent times through contract problems and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now stands trying to achieve expectations - possibly in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers willing to take risks in a tentative opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury in the contest, was competing in only his second appearance at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who worked behind a protective stance to edge the cleaner stanzas.
The audience's tolerance diminished during frequent holding, with Parker falling to the floor several times during grappling.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Hatton Homage Motivates Manchester Derby Battle
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a outstanding all-Manchester battle to win the European light-heavyweight championship.
The venue fell silent for a extremely emotional memorial before the fight as a bell ceremony sounded in honor of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the final chime disappeared, the silence transitioned to a shout of "there's just one Hatton".
The action inside the ropes equaled the feeling. Arthur was knocked down by a left hook flush on the chin in the second round, standing uncertainly to his position on the referee's count.
But the Manchester United-red equipment of Arthur soon advanced again. From the other corner, Rea - in rival City blue - was damaged early, significant bruising appearing under his face as the duo landed powerful shots.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
Arthur edged the result with scoring tallies of draw, close margin and clearer margin, but each competitor were relentless and full of heart, everything their idol Hatton embodied.
