British light-heavyweight Buatsi earned a win yet disappointing beginning to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a split decision in a close ten-round fight at the boxing arena.
But Parker found success, delivering effective single shots in a match where the approaches never quite clicked, with excessive holding spoiling the fight.
Two judges had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They win," Buatsi said in the arena as he was greeted with boos from the crowd.
The Londoner bounced back after his maiden career setback - an thrilling contest with his previous opponent in February - to claim a twentieth professional win.
Several boxing experts thought the challenger, 31, should have been awarded the win but the contender suffered the second defeat of his 28-match career.
The Champion Earns Victory in Uneventful Match
His career development has stalled in the past few years through contract problems and long spells of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a last chance - under fresh management.
He started carefully, with the two boxers ready to be aggressive in a cagey initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was making just his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who worked behind a solid defense to edge the cleaner periods.
The crowd's patience wore thin because of frequent holding, with Parker falling to the floor various instances during clinches.
The underdog closed well, but many rounds were challenging to assess. However, previous titleholder the boxing analyst - working with the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi progresses, but with the presence of heavy hitter David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Tribute Fuels Manchester Derby Battle
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a terrific Manchester vs Manchester fight to capture the continental belt.
The stadium became quiet for a profoundly moving memorial ahead of the contest as 10 bells tolled in honor of local hero Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast match card in the location since Hatton's passing. As the last bell faded, the stillness became a chant of "there's only one Hatton".
The action inside the ropes equaled the sentiment. The eventual winner was floored by a significant blow flush on the face in the initial stage, rising shakily to his footing on the referee's count.
But the Manchester United-red shorts of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was injured quickly, significant bruising forming under his eye as the duo landed powerful shots.
Rea, 27, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur narrowly won the result with judges scorecards of draw, 115-113 and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration Hatton stood for.
