UK light heavyweight Buatsi made a winning yet unimpressive beginning to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a tight ten-round fight at the Manchester venue.
But Parker landed significant shots, connecting with powerful clean blows in a contest where the techniques didn't complement each other, with frequent clinching disrupting the fight.
Two judges scored it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They win," Buatsi said in the ring as he was met by negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to secure a 20th pro success.
Some ringside observers thought the challenger, 31, merited the decision but the contender experienced the second setback of his 28-bout professional journey.
The Champion Secures Triumph in Uneventful Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to fulfil that early promise - maybe in what seems like a last chance - under recent support.
He started carefully, with neither fighter willing to overcommit in a cagey initial rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after breaking his hand mid-fight, was participating in his second bout at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, making life awkward for Buatsi, who operated with a tight guard to edge the better periods.
The crowd's patience diminished during constant clinching, with Parker falling to the floor multiple occasions during clinches.
The underdog closed well, but many rounds were challenging to assess. Although, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor advances, but with the presence of power puncher Benavidez, and Russian champion Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Memorial Fuels All-Manchester Contest
In the co-main event, Arthur defeated Bradley Rea by split-decision in a excellent all-Manchester contest to win the continental championship.
The venue became quiet for a profoundly moving homage ahead of the contest as 10 bells tolled in memory of the city's native Hatton, who died at age 46 in recently.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the final chime faded, the quiet transitioned to a shout of "there's only one Ricky Hatton".
The action during the bout reflected the sentiment. The eventual winner was floored by a significant blow directly to the face in the second round, getting up unsteadily to his position on the referee's count.
But the traditional red shorts of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up quickly, heavy swelling appearing under his orbital area as the fighters traded powerful shots.
The challenger, 27, connected with strong blows but Arthur, 34, responded in kind with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur barely secured the result with scoring tallies of 114-114, 115-113 and clearer margin, but both fighters were persistent and courageous, everything their inspiration the legend stood for.
