British light-heavyweight Buatsi made a winning yet unimpressive beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a tight 10-round bout at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a contest where the techniques failed to mesh, with frequent clinching spoiling the fight.
The officials had it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my best display but how do champions respond? They win," the victor commented in the arena as he was faced disapproval from the audience.
The British fighter got back to winning after his first professional defeat - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Several boxing experts believed the challenger, 31, should have been awarded the victory but the British boxer experienced the second loss of his 28-bout professional journey.
Buatsi Earns Triumph in Uneventful Encounter
The fighter's advancement has stalled in the past few years through promotional disputes and long spells of inactivity.
Once tipped as the future of British boxing, he now is positioned trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with the two boxers ready to take risks in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, causing problems for Buatsi, who operated with a tight guard to barely take the better rounds.
The audience's tolerance diminished because of regular grabbing, with the challenger slipping to the canvas multiple occasions during close exchanges.
The underdog finished the stronger, but multiple periods were hard to judge. However, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still seems difficult.
Hatton Tribute Motivates Local Rivalry Fight
In the co-main event, Arthur beat Rea by close verdict in a excellent all-Manchester contest to capture the continental belt.
The arena fell silent for a deeply poignant memorial prior to the bout as 10 bells rang in memory of the city's native Ricky Hatton, who died aged 46 in September.
It was the premier televised fight night in the urban center since Hatton's death. As the last bell disappeared, the silence transitioned to a shout of "there's just one Hatton".
The competition within the ring matched the emotion. The eventual winner was floored by a powerful punch squarely on the jaw in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red equipment of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was injured soon, heavy swelling forming under his face as the pair landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity hardly diminished over 12 rounds.
The victor barely secured the result with scoring tallies of even score, narrow lead and wider gap, but both fighters were persistent and courageous, exactly what their idol Hatton embodied.
