British light heavyweight Buatsi secured a victory yet underwhelming start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a competitive 10-round fight at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a match where the techniques failed to mesh, with frequent clinching spoiling the fight.
The scoring judges judged it 96-94 to the winner, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," Buatsi said in the arena as he was met by disapproval from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th pro success.
Various analysts believed the challenger, 31, merited the win but the British boxer suffered the second setback of his 28-match professional journey.
The Champion Secures Triumph in Slow Encounter
His career development has slowed in recent times through management issues and extended periods of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to realize his potential - possibly in what appears to be a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to overcommit in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, making life awkward for Buatsi, who worked behind a solid defense to edge the better periods.
The spectators' acceptance wore thin because of frequent holding, with the challenger going down various instances during close exchanges.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
The victor advances, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Inspires All-Manchester Fight
In the co-main event, Arthur defeated Rea by divided decision in a terrific local rivalry contest to win the European light-heavyweight championship.
The stadium grew hushed for a extremely emotional memorial prior to the bout as ten bells tolled in memory of local hero Ricky Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast match card in the city since Hatton's death. As the concluding sound faded, the quiet gave way to a chant of "there's only one Ricky Hatton".
The action during the bout reflected the emotion. The eventual winner was floored by a powerful punch directly to the chin in the early round, rising shakily to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was damaged soon, heavy swelling forming under his eye as the duo landed hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the pace seldom decreased over twelve rounds.
Arthur narrowly won the verdict with official scores of even score, narrow lead and wider gap, but both fighters were persistent and brave, exactly what their hero the legend embodied.
