UK light-heavyweight Buatsi made a winning yet disappointing debut to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a tight ten-round bout at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a match where the approaches never quite clicked, with excessive holding disrupting the contest.
The scoring judges had it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They succeed," Buatsi stated in the ringside as he was faced disapproval from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Various analysts felt Parker, 31, should have been awarded the win but the British boxer suffered the second setback of his 28-match career.
Buatsi Claims Triumph in Slow Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and long spells of lack of fights.
Earlier forecast as the future of the British fight scene, he now stands trying to realize his potential - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter willing to take risks in a calculated initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who utilized a protective stance to edge the cleaner stanzas.
The crowd's patience wore thin during regular grabbing, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were difficult to score. However, former world champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the caliber of heavy hitter David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Hatton Tribute Fuels Local Rivalry Fight
In the supporting bout, Arthur beat Rea by divided decision in a terrific all-Manchester fight to secure the European light heavyweight championship.
The stadium grew hushed for a extremely emotional memorial prior to the bout as 10 bells tolled in remembrance of local hero Ricky Hatton, who passed away at age 46 in recently.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell disappeared, the stillness became a chant of "only one Ricky Hatton".
The competition within the ring reflected the emotion. The eventual winner was knocked down by a powerful punch directly to the face in the initial stage, getting up unsteadily to his feet on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. On the opposite side, the opponent - in rival City blue - was injured early, heavy swelling appearing under his orbital area as the pair exchanged powerful shots.
Rea, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace rarely dropped over the full distance.
The victor narrowly won the decision with judges scorecards of draw, close margin and wider gap, but the two athletes were determined and courageous, everything their idol Hatton stood for.
