UK light heavyweight Buatsi secured a victory yet unimpressive start to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a tight 10-round contest at the Manchester venue.
But the challenger had his moments, delivering effective individual punches in a fight where the styles didn't complement each other, with excessive holding disrupting the action.
Two judges scored it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but how do champions respond? They prevail," the victor said in the ringside as he was met by boos from the audience.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Some ringside observers felt the challenger, 31, merited the win but the British boxer endured the second defeat of his 28-match career.
Buatsi Secures Win in Slow Match
His career development has slowed in recent times through management issues and long spells of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a tentative opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second appearance at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for the favorite, who utilized a protective stance to edge the cleaner periods.
The audience's tolerance diminished amid regular grabbing, with Parker slipping to the canvas multiple occasions during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Battle
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a outstanding all-Manchester fight to win the European light heavyweight championship.
The venue grew hushed for a extremely emotional tribute prior to the bout as a bell ceremony tolled in memory of local hero Ricky Hatton, who passed away aged 46 in last month.
It was the premier televised match card in the urban center since Hatton's death. As the concluding sound faded, the stillness became a chant of "only one Ricky Hatton".
The fighting within the ring matched the feeling. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red shorts of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was injured early, noticeable damage developing under his orbital area as the fighters landed powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor barely secured the decision with judges scorecards of draw, close margin and 115-112, but each competitor were persistent and brave, exactly what their inspiration the legend stood for.
