UK light heavyweight Buatsi earned a win yet unimpressive start to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a tight ten-round bout at the Co-op Live Arena.
But Parker had his moments, connecting with powerful clean blows in a fight where the approaches never quite clicked, with excessive holding marring the fight.
The officials scored it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi said in the ringside as he was met by boos from the crowd.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a twentieth professional win.
Some ringside observers thought Parker, thirty-one, deserved the decision but the contender suffered the second defeat of his 28-match career.
Buatsi Claims Win in Uneventful Encounter
The fighter's advancement has plateaued in the past few years through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to realize his potential - possibly in what seems like a final roll of the dice - under recent support.
He started carefully, with the two boxers willing to overcommit in a tentative opening few rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second fight at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for the favorite, who utilized a protective stance to narrowly win the better stanzas.
The crowd's patience decreased during regular grabbing, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but many rounds were challenging to assess. Although, ex-champion the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi progresses, but with the caliber of power puncher Benavidez, and Russian star Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Motivates Local Rivalry Contest
In the co-main event, Lyndon Arthur defeated Rea by split-decision in a outstanding all-Manchester battle to win the European light-heavyweight belt.
The stadium became quiet for a deeply poignant homage prior to the bout as a bell ceremony tolled in memory of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised match card in the location since Hatton's passing. As the final chime ended, the stillness gave way to a roar of "there's only one Ricky Hatton".
The fighting within the ring equaled the feeling. The eventual winner was floored by a left hook directly to the chin in the early round, standing uncertainly to his feet on the eight count.
But the traditional red equipment of the fighter soon advanced again. From the other corner, Rea - in competitive blue - was marked up early, noticeable damage appearing under his orbital area as the pair landed hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the pace rarely dropped over 12 rounds.
Arthur narrowly won the verdict with official scores of draw, narrow lead and 115-112, but both fighters were relentless and courageous, everything their hero Hatton embodied.
