UK light heavyweight Joshua Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a close 10-round fight at the Manchester venue.
But Parker had his moments, delivering effective clean blows in a match where the styles didn't complement each other, with excessive holding disrupting the fight.
Two judges had it 96-94 for to the winner, with the final judge a even score.
"It wasn't my finest display but what do champions do? They succeed," the victor stated in the ring as he was faced disapproval from the audience.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Various analysts felt Parker, 31, should have been awarded the win but the Derbyshire fighter experienced the second loss of his 28-fight professional journey.
The Champion Claims Triumph in Slow Encounter
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to realize his potential - possibly in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors ready to take risks in a calculated early stages.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was making just his second fight at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for the favorite, who worked behind a tight guard to edge the better stanzas.
The audience's tolerance diminished because of frequent holding, with the challenger falling to the floor several times during clinches.
The underdog closed well, but multiple periods were challenging to assess. Although, ex-champion Carl Frampton - commentating on Dazn - had it particularly wide for Parker, awarding Buatsi just one round.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Homage Fuels Local Rivalry Fight
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a excellent local rivalry contest to secure the European light heavyweight belt.
The venue fell silent for a deeply poignant memorial prior to the bout as a bell ceremony tolled in memory of the city's native Ricky Hatton, who passed away aged 46 in September.
It was the premier televised boxing event in the city since the passing of Hatton. As the last bell disappeared, the quiet gave way to a roar of "there's only one Hatton".
The action inside the ropes reflected the sentiment. Arthur was floored by a powerful punch squarely on the jaw in the early round, getting up unsteadily to his footing on the referee's count.
But the traditional red attire of Arthur soon advanced again. Across the ring, Rea - in opposing blue - was injured quickly, noticeable damage developing under his orbital area as the fighters exchanged hard punches.
Rea, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the action hardly diminished over 12 rounds.
The victor barely secured the result with scoring tallies of even score, 115-113 and clearer margin, but each competitor were determined and brave, everything their idol the legend embodied.
