UK light heavyweight Buatsi secured a victory yet underwhelming debut to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate likely gained him a majority decision in a close 10-round contest at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a match where the styles failed to mesh, with constant grabbing marring the fight.
Two judges judged it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my finest performance but how do champions respond? They win," the victor stated in the ring as he was met by negative reactions from the audience.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Several boxing experts felt the challenger, thirty-one, merited the win but the Derbyshire fighter endured the second defeat of his 28-match career.
The Champion Secures Win in Uneventful Match
His career development has plateaued in recent years through management issues and extended periods of inactivity.
Once tipped as the future of the British fight scene, he now finds himself trying to realize his potential - possibly in what seems like a final roll of the dice - under fresh management.
He started carefully, with the two boxers ready to take risks in a calculated initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was making just his second appearance at light heavyweight.
By the halfway stage, the underdog had kept it close, causing problems for the favorite, who operated with a solid defense to narrowly win the better periods.
The audience's tolerance wore thin because of regular grabbing, with Parker going down various instances during grappling.
The underdog ended stronger, but multiple periods were hard to judge. However, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor moves on, but with the likes of power puncher David Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Ricky Hatton Memorial Motivates Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Rea by close verdict in a terrific all-Manchester contest to secure the continental championship.
The arena grew hushed for a profoundly moving memorial prior to the bout as ten bells tolled in honor of Manchester's own Ricky Hatton, who passed away 46 years old in last month.
It was the premier televised fight night in the city since Hatton's passing. As the final chime disappeared, the silence gave way to a roar of "there's only one Ricky Hatton".
The fighting within the ring reflected the feeling. The eventual winner was floored by a significant blow flush on the chin in the initial stage, standing uncertainly to his position on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured early, noticeable damage forming under his eye as the duo traded powerful shots.
Rea, 27, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the action seldom decreased over twelve rounds.
Arthur barely secured the result with scoring tallies of draw, close margin and wider gap, but the two athletes were persistent and full of heart, exactly what their idol Hatton stood for.
