British light-heavyweight Buatsi made a winning yet unimpressive start to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a split decision in a tight ten-round contest at the boxing arena.
But the challenger found success, connecting with powerful single shots in a fight where the styles didn't complement each other, with excessive holding spoiling the action.
Two judges judged it 96-94 for to Buatsi, with the final judge a 95-95.
"It wasn't my best performance but what defines champions? They win," Buatsi said in the arena as he was faced disapproval from the audience.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to claim a 20th pro success.
Various analysts believed the challenger, thirty-one, deserved the victory but the contender experienced the second defeat of his 28-bout career.
Buatsi Claims Triumph in Slow Match
His career development has stalled in the past few years through management issues and extended periods of lack of fights.
Earlier forecast as the future of the British fight scene, he now finds himself trying to realize his potential - perhaps in what appears to be a last chance - under new promotional backing.
He opened tentatively, with both competitors prepared to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand mid-fight, was participating in his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a tight guard to narrowly win the more effective stanzas.
The crowd's patience decreased during regular grabbing, with Parker slipping to the canvas several times during close exchanges.
The underdog finished the stronger, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - providing analysis for Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Hatton Memorial Fuels Local Rivalry Battle
In the co-main event, Arthur beat Rea by divided decision in a terrific Manchester vs Manchester fight to secure the European light-heavyweight belt.
The venue became quiet for a extremely emotional memorial prior to the bout as 10 bells sounded in honor of Manchester's own Hatton, who succumbed aged 46 in recently.
It was the premier televised boxing event in the city since Hatton's passing. As the concluding sound ended, the stillness became a chant of "there's just one Ricky Hatton".
The action inside the ropes equaled the feeling. The eventual winner was knocked down by a significant blow directly to the jaw in the early round, rising shakily to his position on the eight count.
But the traditional red shorts of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the pair exchanged punishing blows.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the intensity rarely dropped over twelve rounds.
The victor narrowly won the verdict with judges scorecards of even score, close margin and 115-112, but each competitor were relentless and brave, exactly what their inspiration the legend embodied.
