UK light-heavyweight Buatsi earned a win yet unimpressive start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But Parker had his moments, connecting with powerful clean blows in a fight where the styles didn't complement each other, with excessive holding spoiling the contest.
Two judges scored it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what do champions do? They succeed," the victor stated in the ringside as he was faced disapproval from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to claim a 20th pro success.
Some ringside observers believed the challenger, 31, merited the win but the British boxer suffered the second defeat of his 28-bout career.
Buatsi Claims Victory in Slow Affair
His career development has slowed in the past few years through contract problems and considerable time of inactivity.
Once tipped as the next star of British boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a last chance - under recent support.
He started carefully, with both competitors ready to be aggressive in a tentative opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had stayed in contention, making life awkward for the favorite, who operated with a solid defense to edge the cleaner stanzas.
The crowd's patience diminished because of constant clinching, with Parker falling to the floor various instances during grappling.
Parker ended stronger, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
The victor moves on, but with the likes of heavy hitter Benavidez, and Russian champion Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Hatton Memorial Motivates All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a excellent all-Manchester contest to capture the European light-heavyweight belt.
The arena fell silent for a profoundly moving tribute before the fight as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised fight night in the urban center since Hatton's death. As the last bell faded, the stillness gave way to a chant of "there's only one Hatton".
The competition within the ring equaled the emotion. The eventual winner was knocked down by a significant blow squarely on the face in the second round, getting up unsteadily to his footing on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was injured soon, heavy swelling developing under his eye as the pair traded powerful shots.
Rea, 27, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the verdict with scoring tallies of draw, close margin and clearer margin, but the two athletes were determined and full of heart, all the qualities their idol the legend represented.
