British light heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a tight 10-round fight at the Co-op Live Arena.
But the challenger had his moments, delivering effective clean blows in a contest where the approaches failed to mesh, with frequent clinching spoiling the fight.
Two judges scored it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my best performance but what do champions do? They win," the victor said in the ringside as he was faced disapproval from the crowd.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers thought Parker, thirty-one, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-fight professional journey.
Buatsi Earns Win in Dull Affair
The fighter's advancement has stalled in recent years through contract problems and considerable time of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to achieve expectations - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with the two boxers prepared to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss 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 fight's midpoint, the underdog had stayed in contention, causing problems for the favorite, who operated with a tight guard to edge the more effective stanzas.
The audience's tolerance decreased during frequent holding, with the challenger slipping to the canvas various instances during grappling.
The underdog closed well, but many rounds were hard to judge. Although, former world champion the boxing analyst - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
The victor moves on, but with the likes of power puncher David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent local rivalry battle to win the continental belt.
The arena grew hushed for a profoundly moving memorial prior to the bout as ten bells rang in remembrance of local hero Hatton, who died at age 46 in September.
It was the first major televised boxing event in the city since the passing of Hatton. As the final chime faded, the silence became a shout of "there's only one Hatton".
The action within the ring reflected the feeling. Arthur was sent to the canvas by a left hook directly to the chin in the second round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red equipment of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was injured early, significant bruising developing under his eye as the pair traded powerful shots.
The challenger, 27, landed power punches but Arthur, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur barely secured the result with judges scorecards of even score, close margin and 115-112, but the two athletes were persistent and brave, all the qualities their idol Hatton embodied.
