UK light-heavyweight Buatsi earned a win yet unimpressive beginning to life under new promoters with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round fight at the Co-op Live Arena.
But the challenger landed significant shots, landing some telling individual punches in a match where the styles never quite clicked, with frequent clinching spoiling the fight.
The officials had it 96-94 for to Buatsi, with the remaining official a even score.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi commented in the arena as he was met by negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought the challenger, 31, should have been awarded the victory but the contender suffered the second loss of his 28-bout career.
Buatsi Earns Triumph in Dull Match
The fighter's advancement has stalled in recent years through contract problems and long spells of lack of fights.
Previously predicted as the next star of British boxing, he now finds himself trying to realize his potential - maybe in what seems like a last chance - under new promotional backing.
He started carefully, with neither fighter willing to overcommit in a calculated initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who utilized a protective stance to narrowly win the cleaner rounds.
The crowd's patience wore thin amid constant clinching, with the challenger falling to the floor multiple occasions during clinches.
Parker finished the stronger, but several stanzas were hard to judge. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Hatton Tribute Motivates All-Manchester Battle
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a terrific Manchester vs Manchester fight to capture the European light heavyweight belt.
The venue grew hushed for a deeply poignant homage before the fight as 10 bells sounded in honor of Manchester's own Hatton, who died aged 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the concluding sound faded, the quiet transitioned to a shout of "there's only one Ricky Hatton".
The fighting inside the ropes equaled the emotion. The eventual winner was knocked down by a significant blow directly to the jaw in the initial stage, rising shakily to his footing on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. On the opposite side, Rea - in rival City blue - was damaged early, noticeable damage appearing under his orbital area as the duo exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity hardly diminished over twelve rounds.
The victor edged the decision with judges scorecards of draw, close margin and 115-112, but the two athletes were determined and brave, exactly what their inspiration the legend stood for.
