UK light heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a close 10-round contest at the Co-op Live Arena.
But the challenger had his moments, landing some telling individual punches in a contest where the techniques never quite clicked, with constant grabbing marring the action.
The officials judged it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest display but what defines champions? They win," the victor commented in the ring as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with his previous opponent in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, 31, merited the win but the Derbyshire fighter endured the second setback of his 28-match professional journey.
The Champion Earns Win in Uneventful Encounter
His career development has plateaued in recent times through management issues and extended periods of lack of fights.
Previously predicted as the future of the British fight scene, he now is positioned trying to realize his potential - maybe in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter willing to take risks in a tentative opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, making life awkward for Buatsi, who worked behind a protective stance to narrowly win the cleaner rounds.
The crowd's patience wore thin because of frequent holding, with the challenger slipping to the canvas several times during grappling.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just a single round.
The victor moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Homage Fuels Manchester Derby Contest
In the co-main event, Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester fight to secure the continental championship.
The venue became quiet for a profoundly moving memorial ahead of the contest as a bell ceremony tolled in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised fight night in the urban center since Hatton's passing. As the final chime ended, the quiet transitioned to a shout of "there's only one Ricky Hatton".
The competition during the bout reflected the emotion. Arthur was sent to the canvas by a significant blow directly to the chin in the initial stage, standing uncertainly to his footing on the count of eight.
But the traditional red attire of Arthur soon pressed ahead again. From the other corner, the opponent - in competitive blue - was marked up soon, noticeable damage appearing under his orbital area as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, 34, fought fire with fire with powerful upward punches as the action rarely dropped over the full distance.
Arthur barely secured the result with judges scorecards of even score, close margin and clearer margin, but each competitor were relentless and brave, everything their idol the legend stood for.
