UK light heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a competitive ten-round fight at the Co-op Live Arena.
But Parker had his moments, connecting with powerful clean blows in a fight where the techniques didn't complement each other, with constant grabbing disrupting the action.
The officials had it 96-94 for to the winner, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They prevail," the victor said in the ring as he was faced negative reactions from the audience.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Various analysts thought the challenger, 31, should have been awarded the win but the Derbyshire fighter experienced the second setback of his 28-fight career.
Buatsi Earns Win in Dull Encounter
The fighter's advancement has slowed in recent times through contract problems and long spells of inactivity.
Earlier forecast as the future of British boxing, he now finds himself trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter willing to be aggressive in a tentative early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after breaking his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who utilized a tight guard to narrowly win the better rounds.
The spectators' acceptance diminished during frequent holding, with the challenger slipping to the canvas various instances during close exchanges.
The underdog closed well, but multiple periods were hard to judge. Although, former world champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Homage Motivates Local Rivalry Contest
In the co-main event, Lyndon Arthur overcame Rea by divided decision in a terrific all-Manchester battle to secure the European light heavyweight belt.
The venue fell silent for a profoundly moving homage before the fight as ten bells tolled in honor of the city's native Ricky Hatton, who died 46 years old in September.
It was the initial significant broadcast fight night in the urban center since Hatton's passing. As the last bell ended, the quiet became a roar of "there's just one Hatton".
The fighting inside the ropes equaled the emotion. Arthur was floored by a left hook squarely on the jaw in the early round, standing uncertainly to his footing on the referee's count.
But the traditional red shorts of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was marked up soon, noticeable damage appearing under his eye as the duo traded punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur edged the decision with scoring tallies of draw, close margin and wider gap, but each competitor were relentless and brave, exactly what their hero Hatton represented.
