UK light-heavyweight Buatsi earned a win yet unimpressive debut to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a close ten-round fight at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a contest where the styles never quite clicked, with constant grabbing spoiling the contest.
The scoring judges judged it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my best showing but what do champions do? They win," the victor said in the ringside as he was greeted with boos from the audience.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th pro success.
Some ringside observers believed Parker, thirty-one, merited the win but the Derbyshire fighter suffered the second defeat of his 28-fight career.
Buatsi Earns Victory in Dull Encounter
His career development has stalled in the past few years through management issues and considerable time of lack of fights.
Earlier forecast as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what feels like a last chance - under recent support.
He began cautiously, with neither fighter willing to overcommit in a tentative opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand mid-fight, was participating in his second fight at light heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who worked behind a solid defense to edge the better rounds.
The spectators' acceptance decreased because of regular grabbing, with the challenger going down various instances during grappling.
The underdog closed well, but several stanzas were hard to judge. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Hatton Memorial Inspires All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester battle to secure the European light-heavyweight championship.
The arena became quiet for a deeply poignant tribute ahead of the contest as a bell ceremony sounded in memory of Manchester's own Ricky Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast match card in the city since Hatton's passing. As the final chime disappeared, the silence became a chant of "there's only one Hatton".
The competition during the bout equaled the feeling. The eventual winner was knocked down by a powerful punch squarely on the chin in the initial stage, standing uncertainly to his feet on the referee's count.
But the traditional red equipment of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was damaged quickly, noticeable damage appearing under his face as the duo traded punishing blows.
Rea, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur barely secured the result with judges scorecards of draw, 115-113 and wider gap, but each competitor were determined and brave, exactly what their inspiration Hatton stood for.
