UK light heavyweight Buatsi made a winning yet underwhelming debut to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a split decision in a competitive 10-round contest at the Manchester venue.
But the challenger had his moments, landing some telling individual punches in a fight where the approaches never quite clicked, with excessive holding spoiling the action.
The officials judged it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest display but what defines champions? They succeed," Buatsi commented in the ring as he was faced disapproval from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with Callum Smith in last winter - to earn a 20th pro success.
Several boxing experts believed the challenger, 31, merited the decision but the contender suffered the second defeat of his 28-fight career.
The Champion Claims Victory in Slow Encounter
The fighter's advancement has slowed in recent times through promotional disputes and long spells of inactivity.
Previously predicted as the next star of the British fight scene, he now is positioned trying to achieve expectations - possibly in what appears to be a last chance - under recent support.
He began cautiously, with neither fighter ready to take risks in a cagey early stages.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after breaking his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for the favorite, who utilized a protective stance to barely take the more effective stanzas.
The crowd's patience wore thin because of regular grabbing, with Parker slipping to the canvas several times during close exchanges.
Parker ended stronger, but many rounds were difficult to score. However, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, awarding Buatsi just one round.
The victor moves on, but with the caliber of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Homage Motivates All-Manchester Contest
In the supporting bout, Arthur defeated Rea by split-decision in a excellent local rivalry contest to secure the continental championship.
The stadium grew hushed for a profoundly moving memorial ahead of the contest as a bell ceremony tolled in remembrance of local hero Hatton, who passed away aged 46 in recently.
It was the premier televised boxing event in the location since Hatton's death. As the final chime disappeared, the silence transitioned to a shout of "there's only one Ricky Hatton".
The action within the ring reflected the sentiment. The eventual winner was knocked down by a left hook directly to the chin in the second round, getting up unsteadily to his footing on the referee's count.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was injured early, noticeable damage developing under his eye as the pair landed powerful shots.
The challenger, 27, connected with strong blows but Arthur, 34, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
The victor narrowly won the verdict with judges scorecards of draw, close margin and clearer margin, but each competitor were relentless and courageous, all the qualities their inspiration the legend represented.
