UK light-heavyweight Buatsi made a winning yet disappointing start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a majority decision in a close 10-round contest at the boxing arena.
But Parker had his moments, landing some telling clean blows in a match where the approaches didn't complement each other, with constant grabbing marring the contest.
Two judges had it 96-94 for to the winner, with the final judge a even score.
"It wasn't my finest performance but how do champions respond? They win," Buatsi said in the ringside as he was greeted with disapproval from the audience.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a 20th career victory.
Some ringside observers believed the challenger, thirty-one, merited the decision but the contender endured the second loss of his 28-bout career.
Buatsi Secures Win in Slow Affair
His career development has stalled in recent years through management issues and considerable time of lack of fights.
Once tipped as the next star of UK boxing, he now stands trying to realize his potential - maybe in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers prepared to overcommit in a calculated initial rounds.
Parker, 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 bout at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the better periods.
The audience's tolerance wore thin during constant clinching, with Parker falling to the floor several times during close exchanges.
Parker finished the stronger, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, scoring for Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific local rivalry contest to secure the continental championship.
The venue grew hushed for a profoundly moving tribute before the fight as ten bells sounded in memory of the city's native Hatton, who passed away 46 years old in September.
It was the premier televised fight night in the urban center since the passing of Hatton. As the final chime disappeared, the stillness gave way to a roar of "there's just one Hatton".
The action inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the jaw in the early round, rising shakily to his feet on the referee's count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. Across the ring, Rea - in opposing blue - was marked up early, significant bruising developing under his eye as the duo landed punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, fought fire with fire with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur barely secured the verdict with judges scorecards of even score, close margin and clearer margin, but the two athletes were persistent and full of heart, exactly what their idol Hatton embodied.
