UK light-heavyweight Buatsi secured a victory 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 appeared to earn him a majority decision in a competitive 10-round contest at the Manchester venue.
But Parker landed significant shots, delivering effective individual punches in a fight where the styles failed to mesh, with excessive holding disrupting the fight.
The scoring judges scored it 96-94 to the winner, with the final judge a even score.
"It wasn't my best performance but what defines champions? They prevail," Buatsi said in the ringside as he was met by negative reactions from the crowd.
The British fighter got back to winning after his initial pro loss - an thrilling contest with his previous opponent in last winter - to earn a twentieth professional win.
Several boxing experts felt the challenger, 31, merited the decision but the contender endured the second setback of his 28-bout career.
Buatsi Earns Victory in Slow Match
His career development has plateaued in recent years through contract problems and extended periods of lack of fights.
Once tipped as the future of UK boxing, he now stands trying to realize his potential - maybe in what seems like a last chance - under new promotional backing.
He began cautiously, with the two boxers ready to overcommit in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second appearance at light heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who utilized a tight guard to barely take the better stanzas.
The spectators' acceptance wore thin during regular grabbing, with Parker falling to the floor multiple occasions during grappling.
Parker closed well, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher David Benavidez, and Russian champion Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Hatton Tribute Motivates Manchester Derby Fight
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a terrific local rivalry fight to capture the European light-heavyweight championship.
The venue fell silent for a deeply poignant memorial before the fight as a bell ceremony rang in memory of the city's native Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised match card in the location since Hatton's passing. As the last bell faded, the silence became a chant of "only one Hatton".
The action within the ring matched the emotion. The eventual winner was knocked down by a left hook flush on the face in the early round, standing uncertainly to his position on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged soon, heavy swelling appearing under his orbital area as the fighters exchanged hard punches.
Rea, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the pace rarely dropped over 12 rounds.
The victor narrowly won the decision with official scores of even score, 115-113 and wider gap, but the two athletes were determined and full of heart, all the qualities their idol Hatton represented.
