British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a close 10-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective single shots in a contest where the techniques didn't complement each other, with frequent clinching disrupting the fight.
The officials had it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my best showing but what do champions do? They win," Buatsi said in the ring as he was greeted with negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Various analysts believed the challenger, 31, deserved the win but the British boxer endured the second loss of his 28-fight career.
Buatsi Earns Triumph in Uneventful Encounter
His career development has plateaued in the past few years through contract problems and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now stands trying to realize his potential - maybe in what feels like a last chance - under fresh management.
He opened tentatively, with neither fighter prepared to take risks in a calculated opening few rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second appearance at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who worked behind a tight guard to edge the more effective stanzas.
The spectators' acceptance wore thin because of frequent holding, with Parker falling to the floor multiple occasions during grappling.
Parker ended stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder Carl Frampton - working with the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - judging by this showing - still seems difficult.
Hatton Memorial Fuels All-Manchester Contest
In the co-main event, Arthur defeated Bradley Rea by divided decision in a excellent all-Manchester fight to capture the continental title.
The stadium grew hushed for a profoundly moving memorial ahead of the contest as 10 bells sounded in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in last month.
It was the first major televised match card in the city since Hatton's passing. As the concluding sound disappeared, the silence transitioned to a shout of "there's just one Hatton".
The action during the bout matched the emotion. The eventual winner was sent to the canvas by a left hook flush on the face in the second round, getting up unsteadily to his feet on the referee's count.
But the traditional red attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was marked up early, significant bruising forming under his orbital area as the duo landed powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over twelve rounds.
The victor edged the verdict with official scores of even score, close margin and clearer margin, but the two athletes were determined and brave, exactly what their idol the legend embodied.
