UK light heavyweight Buatsi made a winning yet disappointing start to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But the challenger found success, connecting with powerful clean blows in a fight where the techniques failed to mesh, with frequent clinching marring the contest.
The officials had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my greatest showing but what do champions do? They succeed," the victor stated in the ring as he was greeted with negative reactions from the crowd.
The Londoner got back to winning after his first professional defeat - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Various analysts thought the challenger, 31, deserved the decision but the Derbyshire fighter experienced the second setback of his 28-match professional journey.
Buatsi Earns Victory in Uneventful Encounter
The fighter's advancement has stalled in recent years through promotional disputes and considerable time of inactivity.
Once tipped as the next star of British boxing, he now stands trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under fresh management.
He started carefully, with neither fighter ready to overcommit in a tentative opening few rounds.
Parker, whose only previous defeat came at the lower weight class against his former opponent in two years ago after damaging his hand during the bout, was participating in his second fight at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a solid defense to edge the more effective stanzas.
The audience's tolerance decreased amid constant clinching, with Parker falling to the floor multiple occasions during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Although, former world champion Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just one round.
The victor advances, but with the caliber of hard hitter David Benavidez, and Russian champion Dmitry Bivol leading the category, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Fuels All-Manchester Fight
In the co-main event, Arthur defeated Rea by close verdict in a terrific all-Manchester fight to win the continental belt.
The venue fell silent for a profoundly moving memorial ahead of the contest as a bell ceremony rang in honor of the city's native Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised boxing event in the city since Hatton's death. As the concluding sound faded, the stillness transitioned to a roar of "there's just one Hatton".
The competition during the bout matched the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the early round, rising shakily to his feet on the count of eight.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was injured early, noticeable damage developing under his face as the fighters traded powerful shots.
The challenger, 27, landed power punches but the champion, 34, matched the intensity with stinging uppercuts as the intensity hardly diminished over 12 rounds.
Arthur edged the result with judges scorecards of even score, narrow lead and clearer margin, but each competitor were persistent and full of heart, all the qualities their inspiration the legend embodied.
