British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a majority decision in a close ten-round fight at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a contest where the approaches failed to mesh, with frequent clinching disrupting the contest.
The scoring judges had it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my finest showing but what do champions do? They succeed," the victor commented in the ring as he was faced disapproval from the spectators.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the decision but the British boxer endured the second setback of his 28-bout professional journey.
The Champion Earns Victory in Uneventful Encounter
His career development has stalled in the past few years through promotional disputes and extended periods of lack of fights.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a last chance - under fresh management.
He began cautiously, with the two boxers ready to overcommit in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second bout at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a tight guard to edge the better stanzas.
The crowd's patience wore thin during regular grabbing, with Parker going down various instances during clinches.
The underdog closed well, but several stanzas were challenging to assess. However, previous titleholder the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, giving Buatsi just one round.
Buatsi moves on, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the co-main event, Arthur beat Rea by close verdict in a outstanding all-Manchester fight to capture the European light heavyweight title.
The stadium grew hushed for a profoundly moving memorial before the fight as 10 bells sounded in honor of local hero Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the last bell faded, the silence gave way to a roar 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 jaw in the initial stage, standing uncertainly to his feet on the referee's count.
But the traditional red attire of the fighter soon came forward again. Across the ring, Rea - in rival City blue - was injured quickly, heavy swelling forming under his orbital area as the pair exchanged powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the action seldom decreased over twelve rounds.
The victor narrowly won the verdict with official scores of 114-114, close margin and 115-112, but each competitor were persistent and brave, everything their inspiration Hatton embodied.
