UK light heavyweight Joshua Buatsi secured a victory yet unimpressive debut to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a close ten-round fight at the Manchester venue.
But Parker found success, delivering effective individual punches in a contest where the approaches failed to mesh, with excessive holding marring the fight.
The officials had it 96-94 to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but what defines champions? They succeed," the victor commented in the ring as he was greeted with negative reactions from the audience.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts thought Parker, thirty-one, merited the win but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
The Champion Claims Triumph in Dull Match
His career development has slowed in the past few years through management issues and considerable time of lack of fights.
Earlier forecast as the future of the British fight scene, he now stands trying to achieve expectations - possibly in what seems like a last chance - under new promotional backing.
He started carefully, with neither fighter ready to take risks in a calculated initial rounds.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after suffering a hand injury during the bout, was competing in only his second appearance at light-heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for Buatsi, who utilized a protective stance to edge the better periods.
The crowd's patience decreased during constant clinching, with Parker falling to the floor multiple occasions during close exchanges.
Parker finished the stronger, but several stanzas were difficult to score. However, previous titleholder the boxing analyst - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just a single round.
Buatsi advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Hatton Tribute Inspires All-Manchester Fight
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a terrific local rivalry battle to win the continental championship.
The arena became quiet for a deeply poignant tribute before the fight as a bell ceremony rang in remembrance of the city's native Hatton, who died 46 years old in last month.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the final chime ended, the quiet became a shout of "there's only one Hatton".
The action within the ring reflected the emotion. The eventual winner was knocked down by a left hook flush on the jaw in the second round, getting up unsteadily to his feet on the count of eight.
But the red-colored attire of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was marked up soon, noticeable damage appearing under his eye as the fighters landed hard punches.
The challenger, 27, landed power punches but Arthur, 34, fought fire with fire with effective uppercuts as the action rarely dropped over twelve rounds.
Arthur barely secured the result with judges scorecards of even score, 115-113 and wider gap, but each competitor were relentless and full of heart, exactly what their idol the legend represented.
