UK light-heavyweight Buatsi earned a win yet underwhelming debut to life under new promoters with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a split decision in a tight 10-round bout at the boxing arena.
But Parker had his moments, delivering effective clean blows in a fight where the techniques failed to mesh, with frequent clinching spoiling the contest.
The officials scored it 96-94 to the winner, with the final judge a 95-95 draw.
"It wasn't my best display but how do champions respond? They win," the victor said in the arena as he was greeted with disapproval from the crowd.
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 career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the decision but the British boxer suffered the second loss of his 28-fight career.
Buatsi Claims Triumph in Slow Encounter
His career development has stalled in recent years through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with the two boxers ready to take risks in a tentative initial rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who utilized a solid defense to barely take the more effective periods.
The audience's tolerance wore thin because of frequent holding, with the challenger going down several times during close exchanges.
Parker ended stronger, but several stanzas were challenging to assess. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the likes of power puncher Benavidez, and Russian champion Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Motivates Local Rivalry Fight
In the secondary fight, Arthur beat Rea by close verdict in a outstanding all-Manchester battle to capture the European light heavyweight belt.
The stadium fell silent for a profoundly moving tribute ahead of the contest as 10 bells sounded in memory of the city's native Hatton, who passed away at age 46 in recently.
It was the first major televised boxing event in the city since Hatton's death. As the last bell disappeared, the quiet became a shout of "only one Hatton".
The action inside the ropes reflected the sentiment. The eventual winner was knocked down by a powerful punch flush on the jaw in the initial stage, rising shakily to his footing on the eight count.
But the red-colored equipment of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was injured soon, significant bruising forming under his eye as the pair exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with stinging uppercuts as the intensity seldom decreased over 12 rounds.
The victor edged the result with scoring tallies of 114-114, 115-113 and 115-112, but both fighters were persistent and full of heart, exactly what their idol the legend represented.
