UK light heavyweight Buatsi secured a victory yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a close 10-round bout at the Manchester venue.
But Parker had his moments, connecting with powerful single shots in a contest where the styles never quite clicked, with frequent clinching marring the contest.
The officials scored it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest display but what do champions do? They prevail," Buatsi commented in the ringside as he was greeted with negative reactions from the spectators.
The Londoner got back to winning after his maiden career setback - an memorable fight with Callum Smith in February - to secure a 20th career victory.
Several boxing experts believed the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter suffered the second setback of his 28-fight professional journey.
The Champion Claims Win in Dull Match
His career development has slowed in recent years through promotional disputes and considerable time of lack of fights.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to realize his potential - perhaps in what feels like a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to be aggressive in a calculated opening few rounds.
Parker, whose sole prior loss came at super-middleweight against John Ryder in 2022 after suffering a hand injury in the contest, was participating in 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 edge the cleaner rounds.
The audience's tolerance diminished because of constant clinching, with the challenger falling to the floor various instances during clinches.
Parker finished the stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Tribute Motivates Local Rivalry Contest
In the secondary fight, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific local rivalry fight to win the European light heavyweight championship.
The stadium fell silent for a deeply poignant tribute prior to the bout as a bell ceremony rang in honor of local hero Ricky Hatton, who passed away aged 46 in September.
It was the first major televised fight night in the urban center since the passing of Hatton. As the final chime disappeared, the silence gave way to a roar of "only one Hatton".
The fighting during the bout equaled the feeling. The eventual winner was knocked down by a significant blow squarely on the jaw in the initial stage, rising shakily to his feet on the eight count.
But the red-colored equipment of Arthur soon came forward again. From the other corner, the opponent - in competitive blue - was injured quickly, noticeable damage forming under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, 34, responded in kind with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor narrowly won the decision with scoring tallies of even score, 115-113 and clearer margin, but each competitor were determined and brave, everything their hero Hatton stood for.
