UK light heavyweight Buatsi earned a win yet unimpressive beginning to his career under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a split decision in a competitive 10-round fight at the Co-op Live Arena.
But the challenger had his moments, delivering effective individual punches in a fight where the styles failed to mesh, with excessive holding marring the fight.
The officials scored it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest showing but what defines champions? They prevail," the victor said in the ring as he was faced negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to secure a 20th career victory.
Several boxing experts believed Parker, thirty-one, merited the victory but the British boxer endured the second loss of his 28-fight career.
The Champion Secures Win in Dull Affair
His career development has slowed in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the future of UK boxing, he now is positioned trying to fulfil that early promise - maybe in what feels like a ultimate opportunity - under recent support.
He started carefully, with both competitors willing to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after breaking his hand mid-fight, was making just his second fight at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a protective stance to narrowly win the better rounds.
The crowd's patience diminished during frequent holding, with the challenger going down several times during clinches.
The underdog closed well, but several stanzas were hard to judge. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just a single round.
The victor advances, but with the likes of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the supporting bout, Lyndon Arthur defeated Rea by close verdict in a excellent Manchester vs Manchester battle to win the European light-heavyweight title.
The venue grew hushed for a deeply poignant memorial prior to the bout as a bell ceremony rang in honor of local hero Ricky Hatton, who died aged 46 in September.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the concluding sound disappeared, the quiet gave way to a shout of "there's just one Hatton".
The competition inside the ropes reflected the feeling. The eventual winner was floored by a left hook directly to the chin in the second round, getting up unsteadily to his footing on the eight count.
But the traditional red attire of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was injured early, significant bruising appearing under his orbital area as the pair traded hard punches.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with powerful upward punches as the intensity rarely dropped over twelve rounds.
The victor edged the verdict with official scores of draw, 115-113 and 115-112, but each competitor were relentless and courageous, all the qualities their inspiration the legend represented.
