UK light-heavyweight Joshua Buatsi made a winning yet disappointing debut to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a split decision in a competitive 10-round bout at the boxing arena.
But the challenger found success, connecting with powerful individual punches in a fight where the approaches never quite clicked, with constant grabbing disrupting the action.
Two judges had it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my best display but what defines champions? They succeed," the victor said in the arena as he was met by negative reactions from the audience.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to secure a twentieth professional win.
Some ringside observers thought the challenger, thirty-one, deserved the win but the contender experienced the second setback of his 28-bout career.
The Champion Secures Win in Dull Match
His career development has stalled in the past few years through management issues and long spells of inactivity.
Once tipped as the future of British boxing, he now finds himself trying to achieve expectations - perhaps in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter prepared to take risks in a cagey opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was participating in his second bout at light-heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a tight guard to barely take the more effective stanzas.
The audience's tolerance decreased because of constant clinching, with the challenger slipping to the canvas multiple occasions during grappling.
Parker closed well, but many rounds were difficult to score. However, previous titleholder the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the likes of hard hitter Benavidez, and Russian star Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Tribute Motivates Local Rivalry Battle
In the supporting bout, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding local rivalry battle to capture the European light heavyweight championship.
The venue fell silent for a extremely emotional homage prior to the bout as 10 bells tolled in remembrance of the city's native Ricky Hatton, who died aged 46 in September.
It was the first major televised boxing event in the urban center since Hatton's passing. As the last bell faded, the silence became a shout of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the feeling. The eventual winner was knocked down by a significant blow squarely on the jaw in the second round, getting up unsteadily to his footing on the eight count.
But the Manchester United-red attire of Arthur soon came forward again. Across the ring, the opponent - in rival City blue - was marked up early, noticeable damage appearing under his orbital area as the pair landed punishing blows.
The challenger, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the intensity rarely dropped over 12 rounds.
Arthur edged the result with official scores of draw, close margin and wider gap, but the two athletes were persistent and courageous, everything their inspiration the legend represented.
