British light heavyweight Buatsi earned a win yet disappointing beginning to his career under new promoters with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight ten-round fight at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a match where the approaches failed to mesh, with excessive holding spoiling the action.
The officials judged it 96-94 to Buatsi, with the third a even score.
"It wasn't my finest showing but what defines champions? They succeed," Buatsi said in the ring as he was faced disapproval from the crowd.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Several boxing experts thought Parker, thirty-one, deserved the win but the British boxer suffered the second setback of his 28-bout professional journey.
Buatsi Claims Win in Slow Match
Buatsi's progress has plateaued in the past few years through contract problems and extended periods of lack of fights.
Previously predicted as the next star of British boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under new promotional backing.
He opened tentatively, with the two boxers prepared to be aggressive in a calculated opening few rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after damaging his hand during the bout, was competing in only his second fight at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who utilized a protective stance to edge the better stanzas.
The audience's tolerance wore thin during regular grabbing, with the challenger going down various instances during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, giving Buatsi just one round.
Buatsi advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Homage Motivates Manchester Derby Fight
In the co-main event, Arthur defeated Bradley Rea by close verdict in a terrific Manchester vs Manchester contest to capture the continental belt.
The arena fell silent for a profoundly moving tribute prior to the bout as 10 bells tolled in remembrance of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the initial significant broadcast fight night in the location since Hatton's death. As the last bell disappeared, the quiet transitioned to a shout of "only one Ricky Hatton".
The competition during the bout reflected the feeling. The eventual winner was knocked down by a powerful punch directly to the chin in the initial stage, rising shakily to his footing on the referee's count.
But the Manchester United-red equipment of the fighter soon came forward again. From the other corner, the opponent - in rival City blue - was damaged quickly, significant bruising appearing under his eye as the duo exchanged hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, responded in kind with stinging uppercuts as the pace rarely dropped over the full distance.
Arthur edged the decision with judges scorecards of even score, close margin and wider gap, but both fighters were persistent and brave, everything their idol Hatton embodied.
