UK light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a split decision in a close 10-round contest at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a contest where the approaches never quite clicked, with excessive holding spoiling the contest.
Two judges had it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but what do champions do? They win," Buatsi said in the ring as he was met by boos from the spectators.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in February - to claim a 20th pro success.
Various analysts thought the challenger, 31, deserved the win but the Derbyshire fighter experienced the second defeat of his 28-fight career.
The Champion Secures Win in Dull Match
The fighter's advancement has stalled in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of British boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors willing to take risks in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was participating in his second appearance at light heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who worked behind a tight guard to edge the better stanzas.
The spectators' acceptance decreased amid regular grabbing, with Parker falling to the floor various instances during close exchanges.
Parker closed well, but many rounds were hard to judge. However, former world champion the boxing analyst - commentating on Dazn - had it strongly leaning for the challenger, giving Buatsi just only one stanza.
The victor moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Tribute Inspires All-Manchester Battle
In the co-main event, Arthur overcame Rea by divided decision in a outstanding all-Manchester fight to win the European light heavyweight belt.
The stadium fell silent for a deeply poignant tribute before the fight as 10 bells sounded in memory of Manchester's own Hatton, who died 46 years old in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell ended, the stillness transitioned to a shout of "only one Hatton".
The competition during the bout equaled the emotion. Arthur was floored by a significant blow directly to the face in the initial stage, getting up unsteadily to his footing on the count of eight.
But the red-colored equipment of Arthur soon pressed ahead again. On the opposite side, Rea - in opposing blue - was injured quickly, noticeable damage developing under his eye as the pair landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with powerful upward punches as the action rarely dropped over the full distance.
Arthur barely secured the decision with scoring tallies of draw, close margin and clearer margin, but the two athletes were determined and courageous, all the qualities their inspiration Hatton stood for.
