UK light heavyweight Buatsi secured a victory yet disappointing start to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a split decision in a close 10-round bout at the boxing arena.
But the challenger found success, landing some telling clean blows in a contest where the approaches never quite clicked, with constant grabbing spoiling the contest.
The officials judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my greatest showing but what do champions do? They succeed," the victor said in the ring as he was met by negative reactions from the spectators.
The Londoner bounced back after his maiden career setback - an epic battle with his previous opponent in February - to secure a 20th career victory.
Several boxing experts believed the challenger, 31, should have been awarded the victory but the Derbyshire fighter experienced the second setback of his 28-match career.
The Champion Claims Win in Uneventful Affair
Buatsi's progress has plateaued in recent times through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - maybe in what feels like a last chance - under recent support.
He opened tentatively, with the two boxers ready to take risks in a calculated early stages.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after damaging his hand mid-fight, was competing in only his second fight at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who utilized a solid defense to edge the cleaner stanzas.
The audience's tolerance diminished during frequent holding, with Parker going down various instances during clinches.
The underdog closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the caliber of power puncher David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Homage Fuels Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Bradley Rea by split-decision in a excellent all-Manchester fight to capture the European light-heavyweight championship.
The venue fell silent for a profoundly moving memorial prior to the bout as a bell ceremony rang in honor of local hero Ricky Hatton, who died aged 46 in recently.
It was the premier televised fight night in the urban center since Hatton's death. As the concluding sound faded, the stillness gave way to a roar of "there's just one Ricky Hatton".
The fighting inside the ropes equaled the emotion. The eventual winner was knocked down by a left hook flush on the jaw in the second round, standing uncertainly to his feet on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured soon, noticeable damage appearing under his orbital area as the pair exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the decision with official scores of even score, close margin and 115-112, but both fighters were persistent and brave, all the qualities their inspiration Hatton represented.
