British light-heavyweight Buatsi earned a win yet unimpressive beginning to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a close 10-round bout at the Manchester venue.
But Parker had his moments, delivering effective single shots in a match where the approaches didn't complement each other, with constant grabbing spoiling the action.
The scoring judges had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my best display but what defines champions? They prevail," Buatsi commented in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers believed the challenger, 31, deserved the decision but the contender experienced the second setback of his 28-bout professional journey.
Buatsi Secures Triumph in Dull Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to achieve expectations - possibly in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors prepared to overcommit in a tentative early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand during the bout, was making just his second fight at light heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who worked behind a solid defense to barely take the better stanzas.
The crowd's patience decreased because of regular grabbing, with the challenger going down several times during grappling.
The underdog closed well, but many rounds were hard to judge. However, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a excellent local rivalry battle to win the continental belt.
The venue fell silent for a extremely emotional memorial prior to the bout as a bell ceremony rang in honor of Manchester's own Hatton, who succumbed aged 46 in recently.
It was the first major televised match card in the location since the passing of Hatton. As the last bell disappeared, the silence gave way to a chant of "there's only one Ricky Hatton".
The fighting inside the ropes matched the sentiment. The eventual winner was floored by a significant blow flush on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, Rea - in opposing blue - was damaged quickly, significant bruising appearing under his face as the fighters exchanged hard punches.
The challenger, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over twelve rounds.
Arthur barely secured the verdict with judges scorecards of even score, 115-113 and wider gap, but the two athletes were persistent and courageous, exactly what their hero Hatton stood for.
