UK light heavyweight Buatsi made a winning yet unimpressive debut to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a close 10-round bout at the boxing arena.
But the challenger had his moments, delivering effective clean blows in a match where the approaches didn't complement each other, with excessive holding spoiling the action.
The scoring judges had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my finest performance but what do champions do? They succeed," the victor said in the arena as he was met by disapproval from the audience.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, 31, deserved the win but the contender suffered the second setback of his 28-match career.
The Champion Earns Victory in Slow Match
Buatsi's progress has slowed in the past few years through contract problems and long spells of inactivity.
Previously predicted as the future of the British fight scene, he now finds himself trying to achieve expectations - perhaps in what feels like a final roll of the dice - under recent support.
He began cautiously, with both competitors willing to be aggressive in a tentative opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, the underdog had kept it close, making life awkward for Buatsi, who utilized a tight guard to narrowly win the better periods.
The crowd's patience decreased amid constant clinching, with the challenger slipping to the canvas multiple occasions during clinches.
The underdog finished the stronger, but many rounds were hard to judge. Although, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Hatton Memorial Fuels Manchester Derby Battle
In the secondary fight, Arthur beat Rea by split-decision in a excellent all-Manchester battle to win the continental championship.
The arena grew hushed for a extremely emotional homage before the fight as ten bells sounded in honor of the city's native Ricky Hatton, who succumbed 46 years old in recently.
It was the premier televised match card in the location since Hatton's death. As the concluding sound faded, the silence transitioned to a shout of "there's just one Hatton".
The fighting within the ring reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the face in the early round, rising shakily to his position on the referee's count.
But the red-colored attire of the fighter soon advanced again. On the opposite side, Rea - in rival City blue - was damaged soon, heavy swelling developing under his orbital area as the pair landed powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with stinging uppercuts as the pace seldom decreased over twelve rounds.
Arthur narrowly won the decision with official scores of even score, 115-113 and 115-112, but both fighters were persistent and brave, everything their inspiration Hatton represented.
