British light heavyweight Buatsi made a winning yet unimpressive beginning to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a close ten-round bout at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a fight where the styles didn't complement each other, with frequent clinching marring the fight.
The officials scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my best display but how do champions respond? They succeed," the victor said in the arena as he was met by negative reactions from the spectators.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the victory but the contender suffered the second defeat of his 28-match career.
Buatsi Earns Victory in Uneventful Match
His career development has stalled in recent years through management issues and long spells of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what feels like a last chance - under recent support.
He started carefully, with the two boxers prepared to overcommit in a tentative early stages.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was competing in only his second bout at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, causing problems for the favorite, who worked behind a solid defense to narrowly win the better stanzas.
The crowd's patience decreased amid regular grabbing, with the challenger falling to the floor various instances during grappling.
The underdog ended stronger, but many rounds were difficult to score. However, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Tribute Inspires All-Manchester Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight title.
The venue fell silent for a deeply poignant memorial ahead of the contest as 10 bells sounded in remembrance of the city's native Hatton, who succumbed at age 46 in recently.
It was the first major televised match card in the urban center since Hatton's death. As the last bell faded, the silence became a roar of "there's just one Hatton".
The competition during the bout equaled the feeling. The eventual winner was knocked down by a powerful punch flush on the jaw in the early round, getting up unsteadily to his position on the count of eight.
But the traditional red attire of the fighter soon pressed ahead again. From the other corner, Rea - in competitive blue - was injured quickly, significant bruising appearing under his eye as the duo exchanged powerful shots.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action rarely dropped over 12 rounds.
The victor edged the result with scoring tallies of even score, close margin and clearer margin, but each competitor were determined and full of heart, all the qualities their hero the legend embodied.
