British light-heavyweight Buatsi secured a victory yet unimpressive debut to his career under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a tight ten-round fight at the Manchester venue.
But the challenger landed significant shots, connecting with powerful single shots in a match where the techniques never quite clicked, with excessive holding spoiling the action.
Two judges had it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my finest display but what defines champions? They prevail," Buatsi commented in the ringside as he was greeted with disapproval from the crowd.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Various analysts thought Parker, 31, merited the victory but the British boxer endured the second defeat of his 28-match professional journey.
Buatsi Earns Win in Slow Encounter
The fighter's advancement has slowed in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now stands trying to realize his potential - possibly in what seems like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was participating in his second fight at the higher weight class.
By the halfway stage, the underdog had stayed in contention, making life awkward for Buatsi, who operated with a protective stance to barely take the better stanzas.
The audience's tolerance wore thin because of frequent holding, with Parker falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but many rounds were difficult to score. Although, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just a single round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Motivates Local Rivalry Battle
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a outstanding Manchester vs Manchester fight to capture the European light-heavyweight title.
The stadium fell silent for a profoundly moving tribute before the fight as a bell ceremony tolled in memory of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the premier televised match card in the city since Hatton's passing. As the concluding sound faded, the stillness became a shout of "there's only one Hatton".
The competition during the bout reflected the feeling. The eventual winner was floored by a powerful punch directly to the jaw in the second round, standing uncertainly to his feet on the referee's count.
But the traditional red shorts of Arthur soon pressed ahead again. From the other corner, Rea - in rival City blue - was marked up quickly, noticeable damage forming under his orbital area as the fighters exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with effective uppercuts as the pace rarely dropped over 12 rounds.
Arthur narrowly won the verdict with official scores of draw, narrow lead and wider gap, but both fighters were determined and brave, exactly what their inspiration Hatton embodied.
