UK light heavyweight Buatsi earned a win yet unimpressive start to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a competitive ten-round contest at the Manchester venue.
But Parker landed significant shots, connecting with powerful single shots in a contest where the approaches failed to mesh, with excessive holding spoiling the action.
The officials had it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi said in the arena as he was met by disapproval from the crowd.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to earn a 20th pro success.
Various analysts felt the challenger, thirty-one, deserved the win but the Derbyshire fighter experienced the second loss of his 28-bout professional journey.
Buatsi Claims Triumph in Uneventful Match
His career development has slowed in recent years through promotional disputes and extended periods of inactivity.
Earlier forecast as the next star of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors ready to take risks in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second bout at light-heavyweight.
By the halfway stage, Parker had kept it close, causing problems for the favorite, who operated with a solid defense to barely take the cleaner periods.
The crowd's patience diminished amid constant clinching, with Parker falling to the floor multiple occasions during grappling.
The underdog ended stronger, but multiple periods were challenging to assess. Nevertheless, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Fight
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester contest to win the European light heavyweight championship.
The venue fell silent for a deeply poignant homage ahead of the contest as ten bells tolled in memory of the city's native Hatton, who passed away at age 46 in last month.
It was the premier televised boxing event in the urban center since Hatton's passing. As the concluding sound ended, the stillness became a roar of "there's only one Ricky Hatton".
The competition during the bout matched the sentiment. Arthur was sent to the canvas by a significant blow squarely on the chin in the early round, getting up unsteadily to his footing on the eight count.
But the red-colored shorts of the fighter soon came forward again. On the opposite side, Rea - in rival City blue - was marked up quickly, noticeable damage forming under his face as the duo landed hard punches.
The challenger, 27, landed power punches but the champion, thirty-four, matched the intensity with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur barely secured the verdict with judges scorecards of draw, close margin and clearer margin, but both fighters were persistent and courageous, exactly what their inspiration Hatton embodied.
