British light-heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a tight 10-round bout at the Co-op Live Arena.
But the challenger found success, landing some telling clean blows in a contest where the techniques never quite clicked, with excessive holding marring the contest.
The officials had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my best display but what do champions do? They prevail," Buatsi said in the ringside as he was greeted with boos from the spectators.
The British fighter got back to winning after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Various analysts felt Parker, thirty-one, merited the decision but the Derbyshire fighter suffered the second defeat of his 28-bout professional journey.
The Champion Secures Win in Slow Affair
His career development has plateaued in recent years through management issues and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to realize his potential - maybe in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with the two boxers ready to take risks in a cagey opening few rounds.
The challenger, 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 fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who utilized a tight guard to narrowly win the better periods.
The spectators' acceptance decreased because of regular grabbing, with Parker going down several times during clinches.
Parker closed well, but many rounds were difficult to score. However, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, awarding Buatsi just one round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Memorial Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur beat Rea by divided decision in a terrific local rivalry battle to capture the European light-heavyweight belt.
The stadium fell silent for a extremely emotional homage before the fight as 10 bells tolled in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised match card in the city since Hatton's death. As the last bell faded, the silence gave way to a shout of "there's only one Ricky Hatton".
The action inside the ropes reflected the feeling. The eventual winner was floored by a left hook flush on the jaw in the early round, standing uncertainly to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was injured soon, significant bruising forming under his orbital area as the pair landed hard punches.
The challenger, 27, connected with strong blows but the champion, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
The victor barely secured the decision with judges scorecards of 114-114, close margin and wider gap, but both fighters were persistent and brave, everything their idol the legend stood for.
