UK light-heavyweight Buatsi earned a win yet disappointing start to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a close ten-round bout at the Co-op Live Arena.
But Parker had his moments, connecting with powerful single shots in a fight where the styles failed to mesh, with excessive holding disrupting the fight.
The scoring judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my best showing but how do champions respond? They prevail," the victor stated in the ringside as he was met by disapproval from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Various analysts felt Parker, thirty-one, should have been awarded the decision but the British boxer suffered the second setback of his 28-fight career.
The Champion Earns Victory in Dull Match
Buatsi's progress has stalled in recent times through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under fresh management.
He started carefully, with the two boxers ready to be aggressive in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second appearance at light heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for the favorite, who operated with a solid defense to edge the better stanzas.
The crowd's patience decreased during regular grabbing, with Parker going down several times during clinches.
The underdog closed well, but multiple periods were difficult to score. Nevertheless, previous titleholder Carl Frampton - working with Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
The victor advances, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a outstanding Manchester vs Manchester battle to win the European light heavyweight title.
The arena fell silent for a deeply poignant homage before the fight as ten bells sounded in honor of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the final chime ended, the stillness gave way to a shout of "there's only one Hatton".
The fighting during the bout equaled the feeling. Arthur was floored by a powerful punch squarely on the chin in the early round, standing uncertainly to his feet on the eight count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was injured quickly, noticeable damage developing under his face as the fighters traded hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the action hardly diminished over the full distance.
The victor barely secured the result with judges scorecards of even score, 115-113 and wider gap, but each competitor were determined and full of heart, everything their hero the legend stood for.
