British light heavyweight Buatsi made a winning yet underwhelming start to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a competitive ten-round contest at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a match where the approaches never quite clicked, with excessive holding disrupting the action.
The officials had it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," the victor stated in the ringside as he was met by negative reactions from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the victory but the Derbyshire fighter experienced the second loss of his 28-match career.
Buatsi Claims Victory in Dull Encounter
The fighter's advancement has stalled in recent times through promotional disputes and extended periods of inactivity.
Previously predicted as the next star of British boxing, he now is positioned trying to achieve expectations - possibly in what seems like a last chance - under new promotional backing.
He started carefully, with the two boxers prepared to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second appearance at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, causing problems for the favorite, who worked behind a protective stance to barely take the better periods.
The crowd's patience diminished during frequent holding, with Parker going down multiple occasions during clinches.
Parker closed well, but multiple periods were challenging to assess. Although, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Homage Inspires Local Rivalry Fight
In the co-main event, Arthur overcame Rea by split-decision in a excellent Manchester vs Manchester contest to win the European light heavyweight belt.
The arena grew hushed for a extremely emotional tribute prior to the bout as ten bells tolled in memory of the city's native Hatton, who succumbed aged 46 in September.
It was the first major televised boxing event in the urban center since Hatton's death. As the last bell disappeared, the stillness gave way to a shout of "there's just one Ricky Hatton".
The fighting inside the ropes equaled the sentiment. The eventual winner was knocked down by a significant blow squarely on the jaw in the initial stage, getting up unsteadily to his position on the eight count.
But the traditional red attire of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was injured soon, noticeable damage forming under his eye as the duo landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur narrowly won the verdict with judges scorecards of even score, narrow lead and 115-112, but each competitor were relentless and courageous, all the qualities their idol the legend represented.
