British light-heavyweight Buatsi earned a win yet unimpressive debut to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a close ten-round contest at the Manchester venue.
But the challenger landed significant shots, connecting with powerful single shots in a contest where the styles never quite clicked, with constant grabbing marring the contest.
The scoring judges scored it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my greatest showing but what defines champions? They prevail," Buatsi said in the arena as he was greeted with negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an thrilling contest with his previous opponent in February - to earn a 20th pro success.
Some ringside observers believed the challenger, 31, deserved the decision but the Derbyshire fighter suffered the second setback of his 28-bout professional journey.
The Champion Claims Victory in Dull Encounter
Buatsi's progress has slowed in the past few years through management issues and considerable time of lack of fights.
Once tipped as the next star of British boxing, he now finds himself trying to realize his potential - maybe in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors ready to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for the favorite, who utilized a protective stance to barely take the cleaner rounds.
The audience's tolerance diminished because of constant clinching, with the challenger falling to the floor several times during clinches.
Parker ended stronger, but many rounds were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just one round.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Hatton Tribute Fuels Manchester Derby Battle
In the co-main event, Arthur defeated Rea by close verdict in a outstanding local rivalry fight to capture the European light heavyweight title.
The stadium fell silent for a extremely emotional tribute ahead of the contest as 10 bells rang in memory of the city's native Hatton, who died 46 years old in recently.
It was the first major televised boxing event in the city since the passing of Hatton. As the last bell faded, the quiet gave way to a roar of "only one Hatton".
The action during the bout reflected the sentiment. Arthur was knocked down by a left hook directly to the jaw in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, Rea - in competitive blue - was damaged early, heavy swelling appearing under his face as the pair exchanged punishing blows.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with powerful upward punches as the pace rarely dropped over twelve rounds.
The victor narrowly won the verdict with scoring tallies of even score, narrow lead and 115-112, but the two athletes were persistent and courageous, all the qualities their idol the legend embodied.
