UK light heavyweight Buatsi secured a victory yet unimpressive debut to life under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close 10-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling individual punches in a fight where the approaches never quite clicked, with constant grabbing spoiling the action.
Two judges had it 96-94 for to Buatsi, with the final judge a even score.
"It wasn't my best showing but what defines champions? They prevail," Buatsi commented in the ringside as he was faced boos from the audience.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to secure a 20th career victory.
Some ringside observers thought Parker, thirty-one, should have been awarded the win but the contender suffered the second defeat of his 28-bout professional journey.
The Champion Earns Victory in Slow Match
Buatsi's progress has plateaued in recent years through management issues and considerable time of inactivity.
Once tipped as the future of British boxing, he now finds himself trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under recent support.
He began cautiously, with the two boxers prepared to take risks in a calculated opening few rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in 2022 after breaking his hand mid-fight, was participating in his second fight at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who operated with a solid defense to narrowly win the more effective periods.
The spectators' acceptance decreased because of constant clinching, with Parker falling to the floor multiple occasions during grappling.
The underdog ended stronger, but multiple periods were hard to judge. Nevertheless, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the likes of power puncher David Benavidez, and Russian champion Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Hatton Tribute Motivates All-Manchester Contest
In the co-main event, Arthur overcame Rea by split-decision in a outstanding local rivalry fight to win the European light heavyweight belt.
The stadium fell silent for a profoundly moving homage ahead of the contest as a bell ceremony sounded in memory of the city's native Hatton, who succumbed at age 46 in last month.
It was the initial significant broadcast fight night in the city since Hatton's passing. As the last bell disappeared, the silence became a chant of "only one Hatton".
The action within the ring matched the feeling. Arthur was knocked down by a left hook squarely on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the traditional red attire of the fighter soon came forward again. Across the ring, the opponent - in competitive blue - was injured soon, significant bruising appearing under his face as the duo landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the intensity hardly diminished over 12 rounds.
The victor barely secured the decision with official scores of even score, narrow lead and clearer margin, but each competitor were persistent and brave, exactly what their hero the legend stood for.
