UK light-heavyweight Buatsi earned a win yet unimpressive start to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a competitive ten-round fight at the Manchester venue.
But the challenger had his moments, delivering effective clean blows in a match where the approaches didn't complement each other, with constant grabbing disrupting the action.
Two judges judged it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They win," the victor commented in the arena as he was met by negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the win but the Derbyshire fighter suffered the second setback of his 28-bout professional journey.
The Champion Claims Victory in Uneventful Affair
His career development has stalled in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors ready to be aggressive in a tentative initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was competing in only his second appearance at the higher weight class.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who utilized a tight guard to narrowly win the more effective periods.
The crowd's patience diminished because of regular grabbing, with Parker falling to the floor various instances during close exchanges.
The underdog closed well, but several stanzas were difficult to score. Nevertheless, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Tribute Motivates Local Rivalry Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester fight to win the European light heavyweight belt.
The venue fell silent for a profoundly moving memorial ahead of the contest as 10 bells sounded in remembrance of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the premier televised match card in the location since Hatton's passing. As the last bell faded, the quiet transitioned to a chant of "there's just one Hatton".
The competition during the bout matched the feeling. Arthur was sent to the canvas by a significant blow squarely on the face in the initial stage, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red equipment of the fighter soon came forward again. Across the ring, the opponent - in opposing blue - was injured early, heavy swelling forming under his orbital area as the pair exchanged hard punches.
Rea, 27, landed power punches but Arthur, 34, responded in kind with effective uppercuts as the pace rarely dropped over the full distance.
Arthur barely secured the decision with scoring tallies of 114-114, 115-113 and 115-112, but each competitor were determined and brave, all the qualities their idol the legend embodied.
