British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a competitive 10-round fight at the Co-op Live Arena.
But Parker had his moments, landing some telling clean blows in a match where the approaches never quite clicked, with frequent clinching spoiling the fight.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my best display but how do champions respond? They succeed," Buatsi stated in the ringside as he was greeted with negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the win but the Derbyshire fighter experienced the second loss of his 28-bout professional journey.
Buatsi Claims Win in Dull Encounter
Buatsi's progress has stalled in recent years through contract problems and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He started carefully, with the two boxers prepared to take risks in a tentative initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was participating in his second bout at light heavyweight.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who worked behind a tight guard to barely take the cleaner periods.
The audience's tolerance decreased during frequent holding, with Parker going down multiple occasions during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Although, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just one round.
The victor progresses, but with the presence of hard hitter Benavidez, and Russian champion Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Homage Motivates All-Manchester Fight
In the co-main event, Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester contest to win the European light heavyweight belt.
The venue fell silent for a extremely emotional tribute before the fight as ten bells rang in honor of Manchester's own Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast match card in the city since Hatton's passing. As the concluding sound disappeared, the quiet became a chant of "only one Ricky Hatton".
The action inside the ropes equaled the feeling. Arthur was floored by a powerful punch directly to the chin in the initial stage, standing uncertainly to his footing on the eight count.
But the Manchester United-red equipment of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was injured soon, significant bruising developing under his orbital area as the duo exchanged hard punches.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over the full distance.
Arthur narrowly won the result with judges scorecards of draw, 115-113 and clearer margin, but both fighters were determined and courageous, everything their idol Hatton embodied.
