British light heavyweight Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a majority decision in a close 10-round fight at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a match where the approaches didn't complement each other, with constant grabbing spoiling the contest.
The scoring judges scored it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They win," Buatsi commented in the ringside as he was greeted with negative reactions from the audience.
The British fighter got back to winning after his maiden career setback - an epic battle with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts felt Parker, 31, should have been awarded the victory but the contender suffered the second loss of his 28-match professional journey.
Buatsi Earns Victory in Dull Match
His career development has slowed in the past few years through management issues and extended periods of inactivity.
Once tipped as the future of British boxing, he now is positioned trying to realize his potential - possibly in what appears to be a ultimate opportunity - under recent support.
He opened tentatively, with both competitors willing to overcommit in a calculated early stages.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was participating in his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for the favorite, who utilized a solid defense to narrowly win the cleaner stanzas.
The spectators' acceptance decreased because of frequent holding, with Parker going down various instances during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - working with the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Hatton Homage Motivates Manchester Derby Contest
In the secondary fight, Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry battle to win the continental title.
The stadium fell silent for a extremely emotional homage before the fight as 10 bells tolled in remembrance of the city's native Ricky Hatton, who passed away aged 46 in last month.
It was the premier televised match card in the urban center since Hatton's death. As the concluding sound disappeared, the quiet transitioned to a roar of "only one Hatton".
The competition during the bout equaled the feeling. Arthur was sent to the canvas by a significant blow directly to the face in the second round, rising shakily to his feet on the eight count.
But the traditional red shorts of Arthur soon advanced again. Across the ring, the opponent - in competitive blue - was injured quickly, noticeable damage forming under his face as the pair traded hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace rarely dropped over twelve rounds.
Arthur narrowly won the verdict with judges scorecards of 114-114, 115-113 and 115-112, but both fighters were persistent and full of heart, exactly what their inspiration Hatton stood for.
