UK light heavyweight Buatsi made a winning yet underwhelming start to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a majority decision in a competitive ten-round fight at the Co-op Live Arena.
But the challenger had his moments, connecting with powerful single shots in a contest where the styles never quite clicked, with constant grabbing marring the fight.
The scoring judges scored it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my finest display but how do champions respond? They win," the victor said in the ring as he was met by boos from the spectators.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to secure a 20th career victory.
Several boxing experts believed Parker, 31, should have been awarded the win but the Derbyshire fighter experienced the second defeat of his 28-bout professional journey.
The Champion Secures Victory in Uneventful Affair
The fighter's advancement has plateaued in recent years through contract problems and considerable time of lack of fights.
Previously predicted as the future of British boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with neither fighter ready to be aggressive in a tentative opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after breaking his hand mid-fight, was making just his second appearance at light-heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who utilized a protective stance to edge the better rounds.
The crowd's patience diminished amid constant clinching, with Parker falling to the floor various instances during grappling.
Parker closed well, but many rounds were challenging to assess. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor moves on, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Memorial Fuels All-Manchester Contest
In the secondary fight, Arthur beat Bradley Rea by divided decision in a excellent local rivalry contest to win the European light-heavyweight title.
The stadium became quiet for a profoundly moving memorial prior to the bout as a bell ceremony sounded in remembrance of the city's native Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the last bell faded, the quiet transitioned to a chant of "only one Hatton".
The action inside the ropes matched the feeling. The eventual winner was sent to the canvas by a left hook directly to the face in the second round, rising shakily to his feet on the eight count.
But the traditional red equipment of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was injured early, heavy swelling appearing under his orbital area as the duo landed powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with effective uppercuts as the pace hardly diminished over 12 rounds.
The victor edged the decision with judges scorecards of even score, 115-113 and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration Hatton represented.
