UK light heavyweight Buatsi earned a win yet unimpressive start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a split decision in a competitive ten-round bout at the boxing arena.
But the challenger landed significant shots, connecting with powerful individual punches in a fight where the techniques failed to mesh, with constant grabbing marring the contest.
The scoring judges had it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my finest display but what do champions do? They win," the victor stated in the ringside as he was met by disapproval from the audience.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers felt the challenger, 31, should have been awarded the victory but the British boxer endured the second loss of his 28-fight career.
Buatsi Earns Triumph in Dull Affair
The fighter's advancement has stalled in the past few years through management issues and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to achieve expectations - maybe in what feels like a last chance - under new promotional backing.
He opened tentatively, with both competitors ready to be aggressive in a cagey early stages.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after damaging his hand during the bout, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, causing problems for Buatsi, who utilized a solid defense to barely take the more effective stanzas.
The audience's tolerance diminished because of constant clinching, with the challenger slipping to the canvas multiple occasions during clinches.
Parker ended stronger, but several stanzas were challenging to assess. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi moves on, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Tribute Inspires Local Rivalry Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent local rivalry contest to capture the European light-heavyweight belt.
The venue fell silent for a profoundly moving homage before the fight as ten bells sounded in memory of local hero Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast match card in the city since Hatton's death. As the last bell disappeared, the quiet became a roar of "there's just one Hatton".
The competition during the bout matched the emotion. The eventual winner was knocked down by a powerful punch directly to the face in the second round, standing uncertainly to his feet on the count of eight.
But the traditional red attire of the fighter soon pressed ahead again. On the opposite side, Rea - in rival City blue - was damaged soon, noticeable damage appearing under his orbital area as the duo landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with effective uppercuts as the pace rarely dropped over the full distance.
Arthur narrowly won the decision with judges scorecards of 114-114, 115-113 and clearer margin, but the two athletes were persistent and courageous, exactly what their hero the legend embodied.
