Meeting at welterweight in February, Fitch and Penn fought to a three-round majority draw in Sydney, Australia. Judges Sal D'Amato and Chris Lee scored rounds 1 and 2 for Penn, 10-9, then had the third 10-8 in favor of Fitch. Barry Foley saw it 29-28 for Fitch.
Penn pushed the action until midway through the fight, surprising Fitch, a bigger wrestler, by grappling and finishing takedowns. But Fitch, ranked No. 2 at welterweight by ESPN.com, dominated the final period, outlanding the former UFC lightweight and welterweight champion 149-2.
The result, however, was enough for Penn (16-7-2), ranked eighth in the division, to receive an immediate do-over with Fitch (23-3-1).
"Both fighters look to keep it out of the hands of the judges this time," UFC president Dana White said in a statement.
The rematch, a feature bout on Zuffa's Independence Day weekend event at the Mandalay Bay Events Center, joins lightweight fights pitting Melvin Guillard against Shane Roller and George Sotiropoulos versus Evan Dunham.
When Fitch, 33, met Penn in February, it was said to be with top contendership on the line. The UFC has not officially announced if the July bout will share that status.
The announcement of Penn's participation should stem any thoughts of his retirement, something the 32-year-old Hawaiian has contemplated several times throughout his decade in MMA.
Josh Gross covers mixed martial arts for ESPN.com.