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 majority decision in a close 10-round fight at the Co-op Live Arena.
But Parker had his moments, delivering effective individual punches in a fight where the techniques didn't complement each other, with frequent clinching disrupting the fight.
Two judges scored it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my finest performance but what do champions do? They prevail," the victor commented in the arena as he was greeted with boos from the audience.
The Londoner returned to winning ways after his first professional defeat - an epic battle with Callum Smith in February - to earn a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the victory but the contender suffered the second defeat of his 28-bout career.
Buatsi Earns Win in Uneventful Affair
The fighter's advancement has slowed in the past few years through contract problems and considerable time of inactivity.
Previously predicted as the rising talent of the British fight scene, he now finds himself trying to realize his potential - possibly in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to take risks in a cagey initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second fight at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, making life awkward for Buatsi, who utilized a protective stance to narrowly win the cleaner stanzas.
The spectators' acceptance decreased during constant clinching, with Parker going down multiple occasions during grappling.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Tribute Motivates All-Manchester Battle
In the co-main event, Lyndon Arthur defeated Rea by close verdict in a terrific all-Manchester battle to capture the continental title.
The stadium grew hushed for a extremely emotional memorial ahead of the contest as ten bells tolled in remembrance of the city's native Hatton, who succumbed at age 46 in recently.
It was the first major televised boxing event in the urban center since Hatton's death. As the final chime disappeared, the quiet became a roar of "only one Ricky Hatton".
The action within the ring reflected the sentiment. Arthur was sent to the canvas by a significant blow directly to the jaw in the second round, rising shakily to his feet on the eight count.
But the red-colored shorts of Arthur soon advanced again. From the other corner, the opponent - in rival City blue - was injured early, noticeable damage forming under his orbital area as the fighters landed punishing blows.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur edged the result with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were relentless and full of heart, everything their inspiration Hatton embodied.
