UK light-heavyweight Buatsi earned a win yet unimpressive debut to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive 10-round fight at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a match where the techniques never quite clicked, with constant grabbing spoiling the contest.
Two judges judged it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my best display but what defines champions? They succeed," the victor commented in the ring as he was faced disapproval from the spectators.
The British fighter bounced back after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the British boxer experienced the second defeat of his 28-match professional journey.
The Champion Earns Victory in Dull Affair
His career development has stalled in the past few years through management issues and extended periods of lack of fights.
Earlier forecast as the future of UK boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors prepared to take risks in a cagey initial rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second fight at light heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who operated with a tight guard to narrowly win the more effective stanzas.
The audience's tolerance diminished amid constant clinching, with the challenger falling to the floor various instances during clinches.
The underdog ended stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi moves on, but with the caliber of heavy hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Memorial Inspires Local Rivalry Contest
In the supporting bout, Lyndon Arthur overcame Rea by close verdict in a terrific Manchester vs Manchester contest to capture the European light heavyweight belt.
The arena became quiet for a extremely emotional tribute prior to the bout as 10 bells rang in honor of local hero Hatton, who passed away at age 46 in September.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the final chime faded, the silence became a roar of "there's only one Ricky Hatton".
The competition within the ring equaled the sentiment. Arthur was sent to the canvas by a significant blow directly to the chin in the initial stage, getting up unsteadily to his position on the referee's count.
But the traditional red attire of Arthur soon advanced again. From the other corner, the opponent - in rival City blue - was injured early, noticeable damage developing under his eye as the pair landed hard punches.
Rea, 27, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the pace hardly diminished over 12 rounds.
The victor edged the result with official scores of 114-114, narrow lead and wider gap, but each competitor were persistent and courageous, all the qualities their hero the legend stood for.
