UK light-heavyweight Buatsi secured a victory yet unimpressive beginning to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a competitive ten-round fight at the Manchester venue.
But Parker had his moments, landing some telling individual punches in a fight where the approaches failed to mesh, with frequent clinching disrupting the fight.
The scoring judges scored it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but what defines champions? They prevail," the victor commented in the arena as he was greeted with boos from the audience.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in last winter - to claim a twentieth professional win.
Several boxing experts felt the challenger, 31, should have been awarded the decision but the contender suffered the second loss of his 28-bout career.
Buatsi Secures Triumph in Slow Affair
His career development has stalled in recent times through contract problems and considerable time of lack of fights.
Once tipped as the next star of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter willing to take risks in a calculated early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to barely take the cleaner rounds.
The audience's tolerance diminished because of constant clinching, with Parker slipping to the canvas several times during grappling.
Parker finished the stronger, but multiple periods were hard to judge. Although, previous titleholder the boxing analyst - working with Dazn - had it particularly wide for Parker, giving Buatsi just one round.
The victor moves on, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Contest
In the supporting bout, Arthur overcame Rea by split-decision in a terrific Manchester vs Manchester fight to win the European light-heavyweight championship.
The stadium grew hushed for a profoundly moving tribute prior to the bout as a bell ceremony sounded in memory of local hero Ricky Hatton, who passed away 46 years old in September.
It was the first major televised boxing event in the urban center since Hatton's death. As the final chime disappeared, the silence gave way to a shout of "there's only one Ricky Hatton".
The fighting during the bout reflected the emotion. The eventual winner was floored by a left hook squarely on the jaw in the early round, rising shakily to his footing on the count of eight.
But the traditional red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was marked up early, significant bruising forming under his eye as the fighters traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over the full distance.
The victor barely secured the result with judges scorecards of draw, 115-113 and wider gap, but each competitor were relentless and full of heart, all the qualities their idol Hatton represented.
