UK light-heavyweight Buatsi made a winning yet underwhelming start to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a competitive 10-round bout at the Manchester venue.
But the challenger had his moments, delivering effective clean blows in a match where the approaches never quite clicked, with constant grabbing disrupting the action.
The scoring judges had it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest showing but what defines champions? They succeed," Buatsi commented in the ring as he was met by negative reactions from the spectators.
The Londoner got back to winning after his initial pro loss - an thrilling contest with his previous opponent in last winter - to earn a 20th pro success.
Some ringside observers thought Parker, 31, deserved the win but the British boxer suffered the second setback of his 28-bout professional journey.
The Champion Earns Victory in Slow Affair
The fighter's advancement has slowed in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the future of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with neither fighter ready to overcommit in a cagey early stages.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for the favorite, who operated with a solid defense to narrowly win the better rounds.
The spectators' acceptance wore thin because of regular grabbing, with Parker going down various instances during grappling.
Parker closed well, but many rounds were difficult to score. However, former world champion the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
The victor moves on, but with the presence of hard hitter Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Homage Motivates All-Manchester Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a terrific all-Manchester fight to secure the European light heavyweight championship.
The stadium fell silent for a deeply poignant memorial ahead of the contest as ten bells tolled in honor of the city's native Ricky Hatton, who died 46 years old in recently.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound ended, the silence transitioned to a chant of "there's just one Hatton".
The fighting inside the ropes equaled the emotion. Arthur was floored by a left hook squarely on the face in the early round, rising shakily to his position on the count of eight.
But the Manchester United-red equipment of Arthur soon pressed ahead again. Across the ring, the opponent - in competitive blue - was marked up quickly, heavy swelling appearing under his orbital area as the duo exchanged punishing blows.
Rea, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur edged the decision with scoring tallies of draw, close margin and wider gap, but each competitor were persistent and full of heart, everything their idol Hatton stood for.
