UK light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a competitive ten-round contest at the boxing arena.
But the challenger found success, delivering effective clean blows in a match where the styles failed to mesh, with constant grabbing marring the contest.
The officials judged it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest performance but how do champions respond? They win," the victor said in the ringside as he was faced negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to secure a twentieth professional win.
Some ringside observers felt Parker, thirty-one, should have been awarded the decision but the Derbyshire fighter endured the second loss of his 28-fight career.
The Champion Earns Triumph in Uneventful Affair
His career development has stalled in the past few years through promotional disputes and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under fresh management.
He opened tentatively, with neither fighter ready to take risks in a cagey opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light heavyweight.
By the middle rounds, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to barely take the cleaner rounds.
The audience's tolerance decreased because of regular grabbing, with the challenger slipping to the canvas several times during close exchanges.
Parker ended stronger, but many rounds were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor progresses, but with the likes of hard hitter David Benavidez, and Russian star Dmitry Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Inspires Local Rivalry Battle
In the supporting bout, Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry fight to win the European light-heavyweight championship.
The venue grew hushed for a profoundly moving memorial before the fight as a bell ceremony sounded in honor of the city's native Hatton, who succumbed aged 46 in last month.
It was the initial significant broadcast fight night in the city since the passing of Hatton. As the last bell disappeared, the silence gave way to a roar of "only one Ricky Hatton".
The fighting within the ring equaled the emotion. Arthur was knocked down by a left hook directly to the chin in the second round, standing uncertainly to his position on the count of eight.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in rival City blue - was injured quickly, noticeable damage forming under his eye as the fighters landed hard punches.
The challenger, twenty-seven, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
Arthur narrowly won the result with judges scorecards of draw, narrow lead and 115-112, but each competitor were relentless and brave, all the qualities their inspiration Hatton stood for.
