"He was just a great man and I'm truly blessed and honored to be a part of this honoring of him for this week," Gonzalez said of the late Arizona senator.
The five-time All-Star spent eight of his 19 years in the majors with Arizona, helping the franchise win its first and only World Series title in 2001.
He noted he had been a friend of McCain's for "a long time," and the Senator had been a sports fan for all the local teams.
Former Arizona Coyotes star Shane Doan will be one of the other pallbearers, while Arizona Cardinals receiver Larry Fitzgerald is expected to speak at the funeral, according to Chris Cole of the Arizona Republic.
The Diamondbacks also announced a noteworthy contingent from the organization will attend the funeral:
Gonzalez noted he has actually known he would be a pallbearer for a few months:
"Senator McCain's a planner, so I've known for a while. ... First of all, it's an honor. And then secondly, he was still living at the time so it was kind of a strange request," he said.
McCain died Saturday at the age of 81 after a battle with brain cancer. He will be honored several times in different services at varied locations across the country, beginning with Wednesday's ceremony at the Arizona State Capitol.