UK light-heavyweight Buatsi earned a win yet disappointing debut to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a competitive 10-round fight at the boxing arena.
But the challenger landed significant shots, delivering effective single shots in a fight where the techniques never quite clicked, with frequent clinching disrupting the fight.
The scoring judges scored it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi stated in the arena as he was faced boos from the spectators.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts thought Parker, thirty-one, deserved the victory but the Derbyshire fighter endured the second setback of his 28-bout career.
The Champion Earns Win in Slow Match
The fighter's advancement has slowed in recent years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to realize his potential - perhaps in what appears to be a last chance - under new promotional backing.
He opened tentatively, with neither fighter ready to overcommit in a tentative early stages.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after breaking his hand during the bout, was making just his second fight at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who operated with a tight guard to narrowly win the more effective rounds.
The spectators' acceptance wore thin during regular grabbing, with Parker slipping to the canvas several times during close exchanges.
The underdog finished the stronger, but several stanzas were difficult to score. However, ex-champion the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor advances, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Memorial Fuels Local Rivalry Contest
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a excellent local rivalry contest to capture the continental belt.
The arena grew hushed for a deeply poignant homage before the fight as a bell ceremony tolled in honor of the city's native Hatton, who succumbed 46 years old in last month.
It was the first major televised fight night in the urban center since Hatton's passing. As the final chime disappeared, the quiet transitioned to a roar of "there's only one Hatton".
The competition inside the ropes reflected the sentiment. Arthur was knocked down by a significant blow flush on the jaw in the second round, getting up unsteadily to his feet on the referee's count.
But the red-colored equipment of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was injured quickly, heavy swelling appearing under his face as the duo exchanged hard punches.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the pace rarely dropped over 12 rounds.
Arthur edged the decision with official scores of draw, narrow lead and clearer margin, but both fighters were relentless and full of heart, all the qualities their idol Hatton stood for.
