British light-heavyweight Buatsi secured a victory yet unimpressive debut to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a tight ten-round fight at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a contest where the techniques didn't complement each other, with excessive holding marring the contest.
Two judges had it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my best display but how do champions respond? They succeed," Buatsi commented in the ring as he was greeted with disapproval from the crowd.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a 20th career victory.
Various analysts thought Parker, 31, merited the win but the Derbyshire fighter experienced the second loss of his 28-fight professional journey.
Buatsi Claims Win in Slow Encounter
Buatsi's progress has slowed in recent years through promotional disputes and long spells of lack of fights.
Once tipped as the rising talent of British boxing, he now finds himself trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with the two boxers willing to overcommit in a calculated early stages.
Parker, whose sole prior loss came at super-middleweight against John Ryder in two years ago after breaking his hand in the contest, was making just his second appearance at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, making life awkward for Buatsi, who worked behind a solid defense to edge the better stanzas.
The audience's tolerance diminished because of regular grabbing, with Parker falling to the floor various instances during grappling.
The underdog finished the stronger, but many rounds were hard to judge. Although, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Tribute Inspires All-Manchester Battle
In the supporting bout, Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester fight to capture the continental belt.
The arena fell silent for a profoundly moving homage prior to the bout as 10 bells rang in remembrance of Manchester's own Ricky Hatton, who died aged 46 in last month.
It was the first major televised boxing event in the location since Hatton's passing. As the last bell ended, the stillness transitioned to a shout of "there's just one Hatton".
The competition during the bout reflected the emotion. The eventual winner was knocked down by a significant blow flush on the face in the early round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red attire of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was injured quickly, significant bruising appearing under his eye as the duo exchanged powerful shots.
The challenger, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with effective uppercuts as the pace rarely dropped over twelve rounds.
The victor barely secured the verdict with official scores of 114-114, 115-113 and clearer margin, but the two athletes were persistent and courageous, exactly what their inspiration the legend stood for.
