UK light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a majority decision in a competitive 10-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the styles didn't complement each other, with constant grabbing disrupting the contest.
The scoring judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest showing but what defines champions? They succeed," Buatsi stated in the ringside as he was faced disapproval from the audience.
The Londoner got back to winning after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers believed the challenger, 31, merited the win but the Derbyshire fighter experienced the second setback of his 28-match professional journey.
Buatsi Claims Win in Uneventful Match
His career development has slowed in recent years through promotional disputes and long spells of inactivity.
Earlier forecast as the rising talent of UK boxing, he now finds himself trying to realize his potential - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter ready to be aggressive in a cagey initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after damaging his hand in the contest, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for Buatsi, who utilized a protective stance to edge the more effective periods.
The crowd's patience diminished amid constant clinching, with Parker falling to the floor several times during grappling.
Parker closed well, but multiple periods were hard to judge. Nevertheless, former world champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, giving Buatsi just one round.
Buatsi progresses, but with the likes of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Memorial Motivates Local Rivalry Fight
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester fight to capture the continental title.
The arena fell silent for a deeply poignant homage ahead of the contest as a bell ceremony rang in honor of the city's native Ricky Hatton, who died aged 46 in last month.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the last bell disappeared, the quiet gave way to a shout of "there's only one Hatton".
The action inside the ropes reflected the sentiment. The eventual winner was knocked down by a significant blow directly to the chin in the initial stage, getting up unsteadily to his feet on the eight count.
But the traditional red shorts of the fighter soon came forward again. From the other corner, Rea - in rival City blue - was damaged soon, significant bruising appearing under his eye as the fighters landed powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the pace seldom decreased over 12 rounds.
Arthur edged the result with official scores of 114-114, 115-113 and 115-112, but both fighters were determined and brave, exactly what their hero the legend embodied.
