UK light heavyweight Buatsi secured a victory yet unimpressive start to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling individual punches in a contest where the styles didn't complement each other, with excessive holding marring the contest.
The officials judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my best performance but how do champions respond? They succeed," the victor said in the arena as he was met by negative reactions from the crowd.
The British fighter bounced back after his maiden career setback - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers believed the challenger, 31, should have been awarded the win but the British boxer experienced the second defeat of his 28-bout professional journey.
The Champion Earns Win in Slow Match
His career development has plateaued in recent years through contract problems and considerable time of lack of fights.
Earlier forecast as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with the two boxers prepared to take risks in a tentative early stages.
Parker, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who worked behind a solid defense to barely take the more effective periods.
The crowd's patience diminished during frequent holding, with Parker falling to the floor various instances during close exchanges.
The underdog closed well, but many rounds were hard to judge. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi progresses, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Motivates Local Rivalry Fight
In the co-main event, Arthur defeated Bradley Rea by split-decision in a excellent Manchester vs Manchester contest to secure the European light-heavyweight championship.
The arena fell silent for a extremely emotional tribute ahead of the contest as ten bells sounded in remembrance of Manchester's own Hatton, who succumbed aged 46 in recently.
It was the first major televised fight night in the city since the passing of Hatton. As the concluding sound faded, the silence transitioned to a shout of "only one Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was knocked down by a significant blow flush on the face in the second round, standing uncertainly to his position on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was injured early, noticeable damage forming under his eye as the duo exchanged powerful shots.
Rea, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur narrowly won the decision with scoring tallies of even score, close margin and clearer margin, but both fighters were determined and brave, everything their inspiration Hatton stood for.
