British light-heavyweight Buatsi made a winning yet unimpressive debut to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a majority decision in a close ten-round fight at the boxing arena.
But Parker had his moments, delivering effective single shots in a fight where the styles never quite clicked, with constant grabbing marring the fight.
The scoring judges judged it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my best showing but how do champions respond? They succeed," the victor stated in the ring as he was greeted with disapproval from the audience.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts felt the challenger, 31, deserved the victory but the contender experienced the second setback of his 28-fight professional journey.
Buatsi Secures Victory in Uneventful Affair
The fighter's advancement has stalled in the past few years through promotional disputes and considerable time of lack of fights.
Once tipped as the next star of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what seems like a last chance - under recent support.
He started carefully, with both competitors prepared to overcommit in a tentative early stages.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after breaking his hand in the contest, was participating in his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who utilized a solid defense to barely take the more effective rounds.
The crowd's patience diminished amid regular grabbing, with Parker going down several times during clinches.
Parker finished the stronger, but many rounds were hard to judge. Nevertheless, previous titleholder Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
Buatsi progresses, but with the likes of heavy hitter Benavidez, and Russian champion Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur defeated Rea by split-decision in a excellent Manchester vs Manchester battle to capture the European light heavyweight belt.
The stadium fell silent for a deeply poignant tribute prior to the bout as ten bells sounded in honor of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast match card in the location since Hatton's passing. As the final chime faded, the silence became a chant of "there's just one Hatton".
The fighting within the ring equaled the feeling. Arthur was floored by a left hook flush on the face in the second round, rising shakily to his position on the eight count.
But the red-colored equipment of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was injured soon, significant bruising forming under his eye as the pair landed hard punches.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity seldom decreased over twelve rounds.
The victor narrowly won the result with scoring tallies of draw, close margin and 115-112, but each competitor were persistent and brave, everything their hero Hatton represented.
