UK light-heavyweight Buatsi secured a victory yet underwhelming debut to his career under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive ten-round fight at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a fight where the approaches didn't complement each other, with excessive holding disrupting the fight.
The officials had it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best showing but what do champions do? They prevail," Buatsi stated in the ringside as he was met by negative reactions from the spectators.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to earn a twentieth professional win.
Some ringside observers believed Parker, 31, merited the win but the contender experienced the second loss of his 28-bout career.
Buatsi Secures Win in Dull Match
Buatsi's progress has stalled in recent years through management issues and considerable time of lack of fights.
Previously predicted as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under fresh management.
He started carefully, with both competitors ready to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light heavyweight.
By the halfway stage, the underdog had made it competitive, causing problems for the favorite, who utilized a protective stance to barely take the more effective periods.
The audience's tolerance wore thin amid regular grabbing, with Parker going down various instances during clinches.
The underdog closed well, but several stanzas were difficult to score. Although, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just a single round.
Buatsi advances, but with the likes of hard hitter David Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Hatton Memorial Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a excellent Manchester vs Manchester contest to secure the European light-heavyweight belt.
The stadium became quiet for a extremely emotional homage ahead of the contest as ten bells rang in memory of the city's native Hatton, who died at age 46 in September.
It was the premier televised fight night in the urban center since the passing of Hatton. As the concluding sound disappeared, the quiet transitioned to a shout of "there's just one Hatton".
The action during the bout reflected the emotion. The eventual winner was floored by a powerful punch flush on the chin in the second round, getting up unsteadily to his feet on the count of eight.
But the Manchester United-red attire of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up quickly, noticeable damage developing under his face as the pair landed punishing blows.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, responded in kind with powerful upward punches as the action rarely dropped over 12 rounds.
Arthur edged the verdict with judges scorecards of even score, 115-113 and 115-112, but both fighters were persistent and courageous, everything their hero Hatton represented.
