UK light-heavyweight Buatsi secured a victory yet underwhelming debut to his career under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a competitive 10-round bout at the boxing arena.
But the challenger found success, landing some telling clean blows in a match where the approaches failed to mesh, with excessive holding marring the fight.
Two judges judged it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi commented in the ring as he was faced disapproval from the crowd.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to claim a 20th career victory.
Some ringside observers thought Parker, thirty-one, should have been awarded the victory but the contender suffered the second loss of his 28-fight professional journey.
The Champion Secures Triumph in Slow Affair
His career development has stalled in the past few years through promotional disputes and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what feels like a last chance - under fresh management.
He opened tentatively, with the two boxers ready to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second fight at the higher weight class.
By the fight's midpoint, Parker had kept it close, causing problems for Buatsi, who operated with a tight guard to barely take the more effective periods.
The crowd's patience wore thin because of regular grabbing, with the challenger falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just one round.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - judging by this showing - still appears challenging.
Hatton Homage Motivates All-Manchester Battle
In the secondary fight, Arthur beat Rea by close verdict in a outstanding local rivalry contest to secure the European light heavyweight belt.
The arena grew hushed for a deeply poignant tribute ahead of the contest as 10 bells tolled in honor of local hero Ricky Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast fight night in the city since Hatton's death. As the concluding sound ended, the stillness became a roar of "there's only one Ricky Hatton".
The action inside the ropes equaled the feeling. Arthur was sent to the canvas by a left hook flush on the face in the initial stage, standing uncertainly to his feet on the eight count.
But the traditional red shorts of the fighter soon came forward again. From the other corner, the opponent - in opposing blue - was marked up soon, noticeable damage appearing under his eye as the fighters landed punishing blows.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the result with scoring tallies of even score, narrow lead and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration Hatton represented.
