British light-heavyweight Buatsi earned a win yet unimpressive debut to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a split decision in a competitive ten-round bout at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful clean blows in a fight where the styles never quite clicked, with constant grabbing spoiling the action.
Two judges scored it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best showing but what do champions do? They prevail," the victor said in the arena as he was greeted with boos from the crowd.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in last winter - to earn a 20th career victory.
Various analysts thought the challenger, thirty-one, should have been awarded the victory but the contender suffered the second setback of his 28-match career.
Buatsi Claims Victory in Slow Encounter
Buatsi's progress has stalled in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the next star of UK boxing, he now stands trying to achieve expectations - perhaps in what appears to be a last chance - under new promotional backing.
He opened tentatively, with both competitors willing to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent 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, the underdog had made it competitive, making life awkward for Buatsi, who utilized a tight guard to barely take the cleaner stanzas.
The audience's tolerance diminished because of constant clinching, with the challenger going down multiple occasions during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. Although, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian star Bivol leading the category, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Fuels All-Manchester Contest
In the co-main event, Arthur beat Rea by split-decision in a excellent all-Manchester fight to win the European light-heavyweight title.
The arena fell silent for a deeply poignant homage ahead of the contest as ten bells rang in remembrance of local hero Ricky Hatton, who passed away aged 46 in September.
It was the first major televised match card in the location since Hatton's passing. As the concluding sound ended, the silence transitioned to a chant of "there's only one Hatton".
The competition inside the ropes matched the emotion. Arthur was sent to the canvas by a left hook directly to the chin in the initial stage, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was marked up early, heavy swelling forming under his eye as the pair traded powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, thirty-four, matched the intensity with effective uppercuts as the pace rarely dropped over the full distance.
The victor edged the decision with scoring tallies of draw, 115-113 and 115-112, but both fighters were relentless and brave, everything their hero the legend embodied.
