UK light-heavyweight Buatsi made a winning yet disappointing debut to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a tight ten-round bout at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a contest where the styles didn't complement each other, with constant grabbing spoiling the fight.
Two judges judged it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my finest display but what defines champions? They win," the victor said in the ring as he was faced boos from the audience.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to claim a 20th pro success.
Various analysts felt the challenger, thirty-one, merited the win but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
Buatsi Secures Triumph in Dull Match
His career development has plateaued in the past few years through promotional disputes and considerable time of lack of fights.
Earlier forecast as the future of British boxing, he now finds himself trying to achieve expectations - possibly in what feels like a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter willing to overcommit in a tentative opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was participating in his second fight at the higher weight class.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who operated with a protective stance to barely take the better rounds.
The crowd's patience decreased because of constant clinching, with Parker slipping to the canvas multiple occasions during grappling.
Parker ended stronger, but several stanzas were challenging to assess. Nevertheless, ex-champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor progresses, but with the presence of power puncher David Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester battle to capture the European light heavyweight belt.
The stadium grew hushed for a extremely emotional homage ahead of the contest as ten bells sounded in remembrance of Manchester's own Ricky Hatton, who passed away at age 46 in last month.
It was the premier televised fight night in the urban center since the passing of Hatton. As the last bell faded, the silence gave way to a chant of "only one Ricky Hatton".
The action within the ring equaled the emotion. The eventual winner was sent to the canvas by a left hook squarely on the face in the second round, getting up unsteadily to his position on the count of eight.
But the red-colored attire of the fighter soon came forward again. From the other corner, Rea - in rival City blue - was injured early, noticeable damage forming under his face as the fighters landed powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the pace seldom decreased over 12 rounds.
The victor barely secured the result with judges scorecards of even score, close margin and 115-112, but each competitor were persistent and courageous, all the qualities their hero the legend embodied.
