UK light-heavyweight Buatsi made a winning yet unimpressive start to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a split decision in a close 10-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a contest where the styles never quite clicked, with frequent clinching marring the fight.
The officials scored it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my greatest showing but how do champions respond? They succeed," Buatsi said in the arena as he was met by negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers believed the challenger, thirty-one, merited the decision but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Claims Triumph in Dull Affair
The fighter's advancement has stalled in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the future of British boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a last chance - under fresh management.
He opened tentatively, with the two boxers ready to overcommit in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was participating in his second fight at the higher weight class.
By the halfway stage, Parker had made it competitive, making life awkward for the favorite, who worked behind a solid defense to narrowly win the more effective rounds.
The spectators' acceptance decreased amid constant clinching, with the challenger slipping to the canvas multiple occasions during clinches.
The underdog closed well, but multiple periods were hard to judge. Although, previous titleholder Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Motivates Local Rivalry Fight
In the co-main event, Arthur defeated Bradley Rea by divided decision in a excellent all-Manchester battle to secure the European light heavyweight belt.
The arena fell silent for a deeply poignant memorial before the fight as a bell ceremony rang in memory of local hero Hatton, who succumbed aged 46 in recently.
It was the premier televised boxing event in the city since the passing of Hatton. As the concluding sound disappeared, the silence became a shout of "there's only one Hatton".
The competition during the bout matched the feeling. Arthur was knocked down by a significant blow squarely on the face in the early round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, Rea - in opposing blue - was marked up quickly, significant bruising developing under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor edged the result with judges scorecards of draw, 115-113 and 115-112, but the two athletes were relentless and courageous, all the qualities their hero Hatton stood for.
