British light-heavyweight Buatsi secured a victory yet unimpressive start to life under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a close ten-round contest at the boxing arena.
But Parker landed significant shots, connecting with powerful single shots in a match where the techniques failed to mesh, with excessive holding disrupting the contest.
The officials had it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my finest display but what defines champions? They win," Buatsi said in the ringside as he was faced disapproval from the spectators.
The Londoner got back to winning after his maiden career setback - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers believed Parker, 31, merited the decision but the contender experienced the second loss of his 28-match professional journey.
Buatsi Claims Triumph in Dull Encounter
Buatsi's progress has stalled in recent years through management issues and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to achieve expectations - maybe in what seems like a last chance - under fresh management.
He began cautiously, with neither fighter willing to take risks in a calculated initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who utilized a tight guard to narrowly win the more effective stanzas.
The crowd's patience decreased amid constant clinching, with the challenger falling to the floor several times during grappling.
The underdog ended stronger, but many rounds were hard to judge. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the co-main event, Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester contest to win the European light heavyweight championship.
The stadium grew hushed for a extremely emotional tribute before the fight as ten bells sounded in memory of Manchester's own Ricky Hatton, who passed away 46 years old in September.
It was the first major televised fight night in the location since Hatton's death. As the concluding sound faded, the quiet became a roar of "there's just one Hatton".
The fighting inside the ropes equaled the feeling. Arthur was knocked down by a left hook flush on the chin in the initial stage, getting up unsteadily to his feet on the referee's count.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged early, noticeable damage forming under his face as the duo exchanged hard punches.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the action rarely dropped over the full distance.
The victor barely secured the verdict with official scores of 114-114, close margin and 115-112, but each competitor were persistent and brave, exactly what their inspiration the legend embodied.
