British light-heavyweight Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a competitive ten-round fight at the boxing arena.
But Parker landed significant shots, landing some telling individual punches in a fight where the approaches never quite clicked, with frequent clinching disrupting the contest.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They succeed," Buatsi said in the arena as he was faced boos from the audience.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in February - to earn a 20th pro success.
Several boxing experts felt the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter endured the second defeat of his 28-fight professional journey.
Buatsi Secures Triumph in Uneventful Affair
His career development has stalled in recent times through contract problems and extended periods of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to realize his potential - perhaps in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors willing to be aggressive in a tentative early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand mid-fight, was making just his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a tight guard to narrowly win the cleaner stanzas.
The crowd's patience wore thin because of frequent holding, with the challenger going down multiple occasions during close exchanges.
The underdog closed well, but multiple periods were difficult to score. Nevertheless, ex-champion Carl Frampton - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Memorial Fuels All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a excellent all-Manchester fight to secure the European light heavyweight title.
The venue grew hushed for a extremely emotional tribute prior to the bout as 10 bells sounded in honor of Manchester's own Ricky Hatton, who died at age 46 in last month.
It was the initial significant broadcast fight night in the city since the passing of Hatton. As the final chime faded, the silence became a chant of "there's only one Ricky Hatton".
The action during the bout equaled the feeling. The eventual winner was sent to the canvas by a powerful punch squarely on the chin in the initial stage, getting up unsteadily to his position on the count of eight.
But the traditional red shorts of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was injured soon, heavy swelling forming under his orbital area as the pair exchanged hard punches.
The challenger, 27, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action hardly diminished over the full distance.
The victor edged the result with official scores of even score, 115-113 and 115-112, but the two athletes were determined and full of heart, exactly what their hero Hatton stood for.
