British light-heavyweight Buatsi made a winning yet underwhelming start to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a majority decision in a competitive 10-round bout at the Co-op Live Arena.
But the challenger landed significant shots, delivering effective single shots in a match where the techniques failed to mesh, with constant grabbing spoiling the fight.
The scoring judges had it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the ring as he was greeted with negative reactions from the crowd.
The British fighter bounced back after his maiden career setback - an thrilling contest with his previous opponent in February - to earn a 20th pro success.
Several boxing experts felt Parker, 31, deserved the decision but the contender experienced the second loss of his 28-match career.
The Champion Secures Win in Slow Affair
His career development has slowed in recent times through contract problems and long spells of inactivity.
Earlier forecast as the next star of British boxing, he now is positioned trying to realize his potential - possibly in what feels like a final roll of the dice - under recent support.
He started carefully, with both competitors prepared to be aggressive in a cagey opening few rounds.
The challenger, whose only previous defeat came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second bout at light-heavyweight.
By the halfway stage, Parker had kept it close, making life awkward for Buatsi, who worked behind a solid defense to narrowly win the more effective rounds.
The crowd's patience decreased because of frequent holding, with the challenger slipping to the canvas multiple occasions during clinches.
The underdog closed well, but multiple periods were difficult to score. Although, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the likes of hard hitter Benavidez, and Russian star Bivol leading the category, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Motivates Local Rivalry Battle
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a terrific all-Manchester battle to win the continental belt.
The venue became quiet for a deeply poignant homage ahead of the contest as a bell ceremony tolled in memory of the city's native Hatton, who passed away 46 years old in recently.
It was the first major televised boxing event in the city since Hatton's death. As the last bell ended, the silence gave way to a shout of "only one Ricky Hatton".
The competition inside the ropes reflected the sentiment. The eventual winner was knocked down by a left hook directly to the chin in the second round, rising shakily to his feet on the eight count.
But the traditional red equipment of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was injured quickly, significant bruising developing under his eye as the pair traded hard punches.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity seldom decreased over the full distance.
Arthur edged the verdict with official scores of 114-114, 115-113 and wider gap, but both fighters were determined and full of heart, everything their inspiration Hatton represented.
