UK light-heavyweight Buatsi made a winning yet disappointing start to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a tight ten-round contest at the Manchester venue.
But the challenger had his moments, delivering effective individual punches in a contest where the styles didn't complement each other, with frequent clinching disrupting the contest.
The scoring judges judged it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest display but what do champions do? They win," the victor commented in the ring as he was met by boos from the crowd.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to claim a twentieth professional win.
Various analysts felt Parker, 31, should have been awarded the decision but the contender suffered the second loss of his 28-match career.
Buatsi Claims Win in Uneventful Encounter
The fighter's advancement has plateaued in the past few years through promotional disputes and long spells of lack of fights.
Earlier forecast as the rising talent of UK boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with both competitors prepared to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, creating difficulties for Buatsi, who worked behind a solid defense to edge the cleaner stanzas.
The crowd's patience wore thin during constant clinching, with Parker falling to the floor several times during close exchanges.
The underdog finished the stronger, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - commentating on Dazn - had it particularly wide for the challenger, scoring for Buatsi just a single round.
The victor advances, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the supporting bout, Arthur beat Bradley Rea by split-decision in a outstanding all-Manchester battle to capture the continental championship.
The stadium fell silent for a profoundly moving memorial prior to the bout as 10 bells sounded in memory of Manchester's own Hatton, who died aged 46 in September.
It was the premier televised boxing event in the urban center since Hatton's passing. As the last bell disappeared, the quiet transitioned to a chant of "there's just one Ricky Hatton".
The competition during the bout reflected the feeling. The eventual winner was knocked down by a powerful punch directly to the jaw in the early round, rising shakily to his position on the referee's count.
But the traditional red shorts of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was damaged quickly, heavy swelling forming under his orbital area as the fighters exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor edged the verdict with judges scorecards of even score, 115-113 and clearer margin, but the two athletes were persistent and courageous, everything their inspiration Hatton represented.
