British light heavyweight Buatsi made a winning yet unimpressive beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a competitive 10-round fight at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a contest where the approaches didn't complement each other, with constant grabbing marring the contest.
Two judges had it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my finest performance but what defines champions? They win," the victor stated in the ringside as he was met by negative reactions from the spectators.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts felt the challenger, 31, deserved the decision but the Derbyshire fighter endured the second loss of his 28-match professional journey.
The Champion Secures Win in Dull Encounter
The fighter's advancement has slowed in recent years through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He started carefully, with the two boxers willing to overcommit in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after breaking his hand mid-fight, was making just his second fight at the higher weight class.
By the halfway stage, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a protective stance to barely take the better rounds.
The audience's tolerance diminished during constant clinching, with Parker going down multiple occasions during grappling.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still appears challenging.
Hatton Tribute Fuels Local Rivalry Fight
In the co-main event, Arthur overcame Rea by split-decision in a outstanding local rivalry battle to win the European light heavyweight championship.
The venue grew hushed for a profoundly moving homage before the fight as a bell ceremony sounded in honor of Manchester's own Hatton, who succumbed at age 46 in last month.
It was the first major televised boxing event in the city since Hatton's passing. As the concluding sound disappeared, the stillness gave way to a shout of "there's only one Hatton".
The action inside the ropes matched the feeling. The eventual winner was sent to the canvas by a significant blow directly to the face in the early round, standing uncertainly to his position on the count of eight.
But the red-colored attire of the fighter soon advanced again. On the opposite side, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his eye as the fighters exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the action hardly diminished over 12 rounds.
Arthur barely secured the decision with official scores of even score, narrow lead and wider gap, but each competitor were persistent and full of heart, exactly what their inspiration Hatton stood for.
