UK light-heavyweight Buatsi secured a victory yet disappointing debut to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a competitive ten-round contest at the Manchester venue.
But Parker landed significant shots, landing some telling single shots in a contest where the approaches didn't complement each other, with frequent clinching marring the fight.
Two judges had it 96-94 to the winner, with the third a even score.
"It wasn't my greatest performance but what defines champions? They succeed," the victor stated in the arena as he was faced negative reactions from the crowd.
The British fighter bounced back after his first professional defeat - an epic battle with his previous opponent in February - to claim a 20th pro success.
Some ringside observers felt Parker, 31, should have been awarded the win but the contender suffered the second setback of his 28-fight career.
The Champion Earns Victory in Dull Match
His career development has plateaued in the past few years through contract problems and extended periods of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to realize his potential - perhaps in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers prepared to be aggressive in a calculated initial rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand in the contest, was participating in his second fight at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a tight guard to edge the more effective stanzas.
The crowd's patience diminished amid constant clinching, with Parker going down various instances during clinches.
The underdog ended stronger, but several stanzas were difficult to score. However, ex-champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of heavy hitter Benavidez, and Russian champion Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Homage Motivates Local Rivalry Contest
In the co-main event, Arthur beat Bradley Rea by close verdict in a excellent all-Manchester battle to secure the continental championship.
The venue grew hushed for a profoundly moving homage ahead of the contest as ten bells sounded in honor of the city's native Hatton, who died aged 46 in last month.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the final chime disappeared, the quiet gave way to a shout of "there's only one Hatton".
The fighting within the ring equaled the feeling. The eventual winner was sent to the canvas by a left hook directly to the chin in the initial stage, getting up unsteadily to his feet on the referee's count.
But the red-colored equipment of Arthur soon pressed ahead again. On the opposite side, Rea - in competitive blue - was injured quickly, significant bruising developing under his face as the fighters landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur edged the result with official scores of even score, close margin and clearer margin, but both fighters were determined and brave, all the qualities their hero Hatton represented.
