UK light heavyweight Buatsi made a winning yet unimpressive start to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close ten-round fight at the boxing arena.
But the challenger found success, connecting with powerful single shots in a match where the approaches didn't complement each other, with excessive holding disrupting the fight.
The officials judged it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my finest performance but how do champions respond? They prevail," Buatsi said in the ring as he was met by boos from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to secure a 20th pro success.
Several boxing experts believed Parker, thirty-one, should have been awarded the win but the Derbyshire fighter experienced the second loss of his 28-bout career.
Buatsi Secures Win in Uneventful Match
His career development has slowed in recent times through management issues and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to realize his potential - possibly in what feels like a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter prepared to overcommit in a tentative initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after breaking his hand mid-fight, was participating in his second fight at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to barely take the better rounds.
The audience's tolerance diminished amid frequent holding, with the challenger going down various instances during close exchanges.
Parker closed well, but many rounds were difficult to score. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, giving Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Memorial Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a outstanding all-Manchester fight to win the European light heavyweight belt.
The venue grew hushed for a deeply poignant tribute ahead of the contest as 10 bells rang in remembrance of the city's native Hatton, who succumbed 46 years old in recently.
It was the first major televised boxing event in the location since the passing of Hatton. As the last bell faded, the stillness became a chant of "there's just one Hatton".
The action within the ring matched the sentiment. Arthur was floored by a significant blow squarely on the jaw in the early round, rising shakily to his position on the eight count.
But the red-colored equipment of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured early, heavy swelling forming under his orbital area as the fighters traded punishing blows.
Rea, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the action seldom decreased over the full distance.
The victor edged the result with scoring tallies of draw, narrow lead and clearer margin, but the two athletes were relentless and courageous, all the qualities their inspiration Hatton embodied.
