UK light heavyweight Buatsi made a winning yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a judges' verdict in a competitive 10-round contest at the Co-op Live Arena.
But Parker had his moments, connecting with powerful single shots in a fight where the techniques didn't complement each other, with excessive holding spoiling the action.
The officials judged it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my greatest display but how do champions respond? They prevail," the victor said in the ring as he was met by boos from the crowd.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in February - to claim a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter endured the second setback of his 28-fight professional journey.
The Champion Secures Triumph in Uneventful Encounter
Buatsi's progress has slowed in recent years through management issues and long spells of inactivity.
Once tipped as the rising talent of UK boxing, he now finds himself trying to achieve expectations - maybe in what appears to be a last chance - under recent support.
He started carefully, with the two boxers ready to take risks in a cagey early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who operated with a tight guard to barely take the cleaner stanzas.
The crowd's patience wore thin because of regular grabbing, with Parker going down multiple occasions during clinches.
The underdog finished the stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor progresses, but with the likes of heavy hitter David Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Tribute Motivates All-Manchester Fight
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a excellent all-Manchester battle to secure the European light-heavyweight championship.
The stadium grew hushed for a deeply poignant homage before the fight as 10 bells sounded in honor of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast match card in the location since Hatton's death. As the last bell faded, the stillness transitioned to a chant of "there's just one Hatton".
The competition within the ring reflected the emotion. Arthur was sent to the canvas by a powerful punch squarely on the chin in the second round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged early, significant bruising developing under his orbital area as the fighters traded powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur narrowly won the decision with judges scorecards of draw, close margin and 115-112, but both fighters were persistent and brave, everything their hero Hatton embodied.
