British light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a close 10-round fight at the Manchester venue.
But Parker landed significant shots, landing some telling single shots in a match where the styles never quite clicked, with frequent clinching marring the contest.
The scoring judges scored it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my finest showing but what defines champions? They prevail," the victor commented in the ring as he was faced negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts believed the challenger, thirty-one, deserved the decision but the Derbyshire fighter endured the second defeat of his 28-match professional journey.
Buatsi Secures Victory in Uneventful Affair
His career development has plateaued in the past few years through management issues and long spells of lack of fights.
Previously predicted as the next star of the British fight scene, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He started carefully, with the two boxers prepared to take risks in a tentative initial rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand in the contest, was participating in his second bout at the higher weight class.
By the halfway stage, the underdog had made it competitive, making life awkward for the favorite, who worked behind a protective stance to edge the better rounds.
The crowd's patience wore thin during constant clinching, with the challenger going down various instances during grappling.
The underdog closed well, but multiple periods were difficult to score. However, ex-champion the boxing analyst - commentating on Dazn - had it particularly wide for Parker, scoring for Buatsi just a single round.
The victor advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires Local Rivalry Fight
In the supporting bout, Arthur beat Rea by close verdict in a outstanding Manchester vs Manchester battle to secure the European light heavyweight championship.
The arena fell silent for a extremely emotional memorial prior to the bout as 10 bells rang in remembrance of Manchester's own Hatton, who succumbed aged 46 in September.
It was the premier televised match card in the city since Hatton's passing. As the concluding sound disappeared, the silence transitioned to a shout of "only one Ricky Hatton".
The fighting within the ring matched the sentiment. Arthur was floored by a significant blow flush on the jaw in the second round, rising shakily to his footing on the referee's count.
But the traditional red shorts of Arthur soon advanced again. From the other corner, the opponent - in rival City blue - was damaged quickly, noticeable damage appearing under his face as the duo traded hard punches.
The challenger, 27, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over twelve rounds.
Arthur barely secured the decision with scoring tallies of 114-114, close margin and clearer margin, but both fighters were persistent and courageous, everything their idol Hatton represented.
