The 33-year-old Leeds prop, who has been an international skipper since taking the Great Britain armband in 2005, missed last year's Four Nations series with a knee injury.
James Graham captained England in his absence, but Peacock is back in the squad and back leading from the front for the clash with Brian McClennan's all-stars at Headingley.
"Jamie missed the tour last year due to his injury but he has worked extremely hard to get back," McNamara said. "He's a huge influence both on the field and off the field and his presence is very much welcomed back."
Peacock only returned to action at the end of April after an eight-month lay-off, and admitted he had to return sooner than he had planned to prove to McNamara that he was ready for selection.
"I knew I had to come back and play very well and come back earlier than I'd have liked," he said. "I knew I needed to have five or six games rather than two or three.
"We have strong leaders anyway, so it's a good group to captain owing to the amount of leaders we have."
McClennan, a double Super League-winning coach with Leeds in 2008 and 2009, also named his final three coach's picks, taking his party up to 22.
Huddersfield forward David Fa'alogo returns after withdrawing with injury last week, while Wakefield's Glenn Morrison and St Helens' Josh Perry have been included.