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 split decision in a close 10-round bout at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful individual punches in a contest where the techniques didn't complement each other, with constant grabbing marring the fight.
Two judges had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but how do champions respond? They win," the victor commented in the ringside as he was greeted with boos from the crowd.
The British fighter bounced back after his maiden career setback - an thrilling contest with Callum Smith in last winter - to claim a 20th career victory.
Various analysts thought the challenger, 31, deserved the decision but the British boxer suffered the second defeat of his 28-fight professional journey.
The Champion Secures Triumph in Slow Affair
Buatsi's progress has stalled in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He began cautiously, with both competitors ready to take risks in a tentative initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after breaking his hand in the contest, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who operated with a tight guard to barely take the better stanzas.
The spectators' acceptance wore thin because of regular grabbing, with the challenger going down multiple occasions during close exchanges.
The underdog closed well, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Hatton Homage Fuels Local Rivalry Fight
In the co-main event, Lyndon Arthur beat Rea by divided decision in a excellent local rivalry fight to secure the European light-heavyweight title.
The arena fell silent for a extremely emotional homage prior to the bout as a bell ceremony rang in remembrance of local hero Ricky Hatton, who died 46 years old in last month.
It was the first major televised match card in the city since the passing of Hatton. As the final chime ended, the quiet transitioned to a chant of "only one Hatton".
The competition inside the ropes equaled the feeling. Arthur was floored by a significant blow directly to the face in the initial stage, standing uncertainly to his feet on the count of eight.
But the red-colored attire of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was marked up quickly, significant bruising forming under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with effective uppercuts as the action hardly diminished over 12 rounds.
Arthur barely secured the verdict with scoring tallies of draw, narrow lead and clearer margin, but the two athletes were relentless and full of heart, exactly what their inspiration the legend embodied.
