UK light heavyweight Buatsi secured a victory yet disappointing debut to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive ten-round bout at the Co-op Live Arena.
But Parker landed significant shots, landing some telling clean blows in a contest where the styles failed to mesh, with excessive holding marring the fight.
The scoring judges scored it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my finest display but what defines champions? They win," the victor said in the ring as he was faced negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th career victory.
Several boxing experts felt Parker, 31, deserved the decision but the British boxer endured the second defeat of his 28-bout professional journey.
Buatsi Claims Win in Dull Affair
The fighter's advancement has slowed in the past few years through management issues and considerable time of lack of fights.
Earlier forecast as the future of UK boxing, he now finds himself trying to realize his potential - maybe in what feels like a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to overcommit in a tentative early stages.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after breaking his hand in the contest, was competing in only his second appearance at the higher weight class.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to narrowly win the better stanzas.
The audience's tolerance decreased during regular grabbing, with the challenger going down various instances during close exchanges.
Parker finished the stronger, but many rounds were hard to judge. Although, former world champion the boxing analyst - providing analysis for Dazn - had it particularly wide for the challenger, awarding Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Hatton Tribute Motivates Manchester Derby Battle
In the co-main event, Arthur overcame Bradley Rea by split-decision in a excellent all-Manchester battle to secure the continental belt.
The venue grew hushed for a profoundly moving memorial prior to the bout as 10 bells tolled in memory of Manchester's own Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the last bell disappeared, the silence transitioned to a chant of "only one Hatton".
The competition during the bout reflected the emotion. The eventual winner was sent to the canvas by a powerful punch directly to the jaw in the initial stage, standing uncertainly to his footing on the referee's count.
But the traditional red shorts of Arthur soon pressed ahead again. On the opposite side, Rea - in competitive blue - was injured quickly, heavy swelling forming under his orbital area as the fighters exchanged powerful shots.
The challenger, 27, connected with strong blows but the champion, thirty-four, responded in kind with effective uppercuts as the pace seldom decreased over twelve rounds.
Arthur narrowly won the result with official scores of even score, narrow lead and clearer margin, but each competitor were persistent and full of heart, everything their inspiration Hatton represented.
