British light heavyweight Buatsi made a winning yet unimpressive beginning to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output appeared to earn him a split decision in a competitive ten-round fight at the Manchester venue.
But Parker had his moments, delivering effective individual punches in a contest where the techniques never quite clicked, with frequent clinching spoiling the action.
The scoring judges judged it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my best showing but how do champions respond? They prevail," the victor commented in the ring as he was greeted with boos from the spectators.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th career victory.
Several boxing experts believed the challenger, 31, merited the decision but the Derbyshire fighter endured the second defeat of his 28-bout career.
Buatsi Secures Win in Slow Affair
His career development has slowed in the past few years through promotional disputes and long spells of lack of fights.
Previously predicted as the future of the British fight scene, he now finds himself trying to realize his potential - maybe in what seems like a ultimate opportunity - under fresh management.
He started carefully, with neither fighter willing to take risks in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after damaging his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, making life awkward for the favorite, who utilized a solid defense to barely take the cleaner stanzas.
The spectators' acceptance wore thin because of constant clinching, with the challenger going down several times during grappling.
The underdog ended stronger, but multiple periods were hard to judge. Although, previous titleholder the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just a single round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Motivates Manchester Derby Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by close verdict in a outstanding local rivalry contest to secure the European light heavyweight belt.
The arena grew hushed for a profoundly moving tribute before the fight as a bell ceremony rang in memory of local hero Hatton, who passed away aged 46 in recently.
It was the first major televised fight night in the city since Hatton's death. As the concluding sound disappeared, the silence gave way to a roar of "there's only one Ricky Hatton".
The fighting during the bout matched the emotion. Arthur was sent to the canvas by a left hook flush on the chin in the initial stage, standing uncertainly to his position on the eight count.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, Rea - in rival City blue - was damaged soon, significant bruising appearing under his orbital area as the duo landed powerful shots.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the action hardly diminished over 12 rounds.
The victor narrowly won the result with scoring tallies of draw, narrow lead and 115-112, but the two athletes were determined and brave, everything their hero the legend represented.
