British light-heavyweight Buatsi made a winning yet underwhelming debut to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight 10-round bout at the boxing arena.
But the challenger landed significant shots, delivering effective individual punches in a match where the techniques never quite clicked, with excessive holding disrupting the fight.
The officials scored it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my best display but what do champions do? They succeed," Buatsi stated in the ringside as he was faced boos from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the decision but the British boxer suffered the second setback of his 28-fight career.
Buatsi Secures Win in Slow Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors ready to take risks in a calculated opening few rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was participating in his second appearance at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to narrowly win the better periods.
The spectators' acceptance diminished during frequent holding, with the challenger slipping to the canvas multiple occasions during close exchanges.
Parker closed well, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, giving Buatsi just only one stanza.
The victor moves on, but with the caliber of power puncher Benavidez, and Russian star Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Hatton Memorial Inspires Local Rivalry Contest
In the co-main event, Lyndon Arthur defeated Rea by divided decision in a terrific local rivalry contest to win the European light-heavyweight championship.
The stadium grew hushed for a deeply poignant homage ahead of the contest as 10 bells sounded in remembrance of local hero Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the location since Hatton's passing. As the concluding sound ended, the stillness became a roar of "there's just one Ricky Hatton".
The competition during the bout equaled the feeling. Arthur was knocked down by a significant blow flush on the face in the early round, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was injured quickly, heavy swelling forming under his face as the fighters traded punishing blows.
Rea, 27, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the pace rarely dropped over 12 rounds.
The victor barely secured the verdict with official scores of draw, narrow lead and 115-112, but both fighters were persistent and courageous, everything their idol Hatton stood for.
