UK light-heavyweight Buatsi secured a victory yet disappointing debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a close ten-round bout at the boxing arena.
But the challenger had his moments, landing some telling single shots in a fight where the techniques didn't complement each other, with constant grabbing disrupting the contest.
The scoring judges judged it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest showing but what defines champions? They prevail," the victor said in the ring as he was met by negative reactions from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Several boxing experts believed Parker, 31, should have been awarded the decision but the Derbyshire fighter experienced the second loss of his 28-bout professional journey.
The Champion Earns Victory in Slow Match
Buatsi's progress has stalled in recent years through management issues and long spells of lack of fights.
Previously predicted as the future of British boxing, he now stands trying to realize his potential - perhaps in what seems like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to take risks in a calculated early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who utilized a protective stance to edge the better stanzas.
The audience's tolerance wore thin during frequent holding, with the challenger going down several times during grappling.
The underdog closed well, but multiple periods were hard to judge. Although, ex-champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor advances, but with the likes of heavy hitter David Benavidez, and Russian star Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Memorial Fuels All-Manchester Contest
In the supporting bout, Arthur defeated Rea by divided decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight title.
The venue fell silent for a profoundly moving homage ahead of the contest as ten bells tolled in memory of local hero Hatton, who died 46 years old in recently.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the last bell disappeared, the silence became a roar of "only one Ricky Hatton".
The action inside the ropes matched the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the chin in the second round, rising shakily to his feet on the count of eight.
But the traditional red equipment of Arthur soon came forward again. From the other corner, the opponent - in competitive blue - was marked up quickly, significant bruising developing under his eye as the fighters landed hard punches.
The challenger, 27, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the pace hardly diminished over the full distance.
Arthur narrowly won the result with scoring tallies of draw, 115-113 and clearer margin, but the two athletes were relentless and brave, exactly what their inspiration the legend stood for.
