UK light-heavyweight Buatsi secured a victory yet underwhelming debut to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive ten-round contest at the Manchester venue.
But the challenger found success, landing some telling individual punches in a match where the approaches didn't complement each other, with constant grabbing marring the fight.
The officials judged it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my finest showing but what do champions do? They succeed," Buatsi stated in the ringside as he was greeted with disapproval from the audience.
The British fighter got back to winning after his maiden career setback - an thrilling contest with Callum Smith in February - to secure a 20th pro success.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the British boxer experienced the second loss of his 28-match professional journey.
Buatsi Earns Triumph in Slow Encounter
His career development has plateaued in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with the two boxers willing to be aggressive in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after breaking his hand in the contest, was making just his second fight at light heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who operated with a protective stance to narrowly win the more effective rounds.
The spectators' acceptance diminished during regular grabbing, with Parker going down multiple occasions during clinches.
The underdog closed well, but multiple periods were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Memorial Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Rea by close verdict in a terrific all-Manchester contest to capture the European light-heavyweight championship.
The venue grew hushed for a deeply poignant homage prior to the bout as 10 bells sounded in memory of local hero Hatton, who died 46 years old in last month.
It was the initial significant broadcast fight night in the city since Hatton's death. As the concluding sound disappeared, the quiet gave way to a shout of "there's just one Hatton".
The competition during the bout reflected the sentiment. Arthur was knocked down by a left hook squarely on the face in the second round, rising shakily to his footing on the referee's count.
But the traditional red equipment of the fighter soon came forward again. Across the ring, the opponent - in rival City blue - was damaged quickly, heavy swelling developing under his eye as the fighters landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the pace rarely dropped over the full distance.
The victor edged the result with official scores of even score, narrow lead and clearer margin, but the two athletes were relentless and brave, exactly what their idol the legend stood for.
