UK light heavyweight Buatsi secured a victory yet disappointing start to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a split decision in a competitive 10-round bout at the boxing arena.
But Parker found success, connecting with powerful clean blows in a fight where the approaches never quite clicked, with excessive holding disrupting the fight.
The officials judged it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They prevail," the victor said in the ringside as he was greeted with boos from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers felt Parker, thirty-one, should have been awarded the win but the British boxer experienced the second defeat of his 28-fight professional journey.
Buatsi Earns Triumph in Dull Match
His career development has slowed in recent times through management issues and long spells of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to achieve expectations - maybe in what feels like a final roll of the dice - under fresh management.
He started carefully, with neither fighter willing to overcommit in a calculated early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was making just his second bout at light heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who operated with a tight guard to narrowly win the more effective periods.
The spectators' acceptance diminished during frequent holding, with Parker going down multiple occasions during close exchanges.
The underdog finished the stronger, but multiple periods were difficult to score. Although, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Fuels Manchester Derby Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a outstanding local rivalry fight to capture the continental title.
The arena fell silent for a extremely emotional tribute ahead of the contest as ten bells rang in honor of local hero Ricky Hatton, who succumbed aged 46 in recently.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the last bell disappeared, the silence became a shout of "only one Hatton".
The competition within the ring matched the emotion. The eventual winner was floored by a powerful punch flush on the face in the second round, standing uncertainly to his position on the eight count.
But the red-colored shorts of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was injured soon, heavy swelling developing under his orbital area as the duo traded hard punches.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over twelve rounds.
Arthur barely secured the verdict with official scores of 114-114, narrow lead and 115-112, but the two athletes were relentless and brave, everything their inspiration the legend stood for.
