UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker had his moments, connecting with powerful single shots in a match where the techniques failed to mesh, with excessive holding spoiling the fight.
Two judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my best showing but how do champions respond? They succeed," Buatsi stated in the ring as he was faced boos from the spectators.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to claim a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the decision but the Derbyshire fighter suffered the second setback of his 28-bout professional journey.
Buatsi Claims Win in Uneventful Affair
Buatsi's progress has slowed in the past few years through promotional disputes and considerable time of lack of fights.
Once tipped as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under recent support.
He began cautiously, with neither fighter prepared to take risks in a tentative early stages.
The challenger, whose sole prior loss 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 fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who worked behind a solid defense to narrowly win the more effective stanzas.
The crowd's patience diminished during regular grabbing, with Parker going down multiple occasions during clinches.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi advances, but with the presence of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester fight to secure the European light heavyweight championship.
The arena grew hushed for a extremely emotional tribute before the fight as 10 bells tolled in remembrance of the city's native Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the concluding sound disappeared, the quiet became a chant of "there's just one Hatton".
The competition within the ring reflected the emotion. The eventual winner was knocked down by a significant blow squarely on the chin in the early round, getting up unsteadily to his position on the referee's count.
But the traditional red equipment of the fighter soon advanced again. From the other corner, the opponent - in competitive blue - was injured early, significant bruising developing under his face as the fighters traded powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over 12 rounds.
The victor narrowly won the result with official scores of even score, narrow lead and wider gap, but the two athletes were relentless and full of heart, all the qualities their hero the legend stood for.
