Townsend, who has appeared in the films "Queen of the Damned" and "About Adam," made the remarks while he and Theron were at the Toronto International Film Festival to promote "Battle in Seattle," Townsend's directorial debut.
Theron plays a role in the movie and stars in another festival highlight, "In the Valley of Elah."
The couple started dating seven years ago after they met on the set of the movie "Trapped."
"I'm married," Townsend told People.
"I didn't do a church wedding or anything but we're married. We're husband and wife. We love each other and we want to spend our lives together," the actor said of Theron, whom he calls "the greatest woman I've ever met."
"There's no big official story on a wedding, but we are married. ... I consider her my wife and she considers me her husband," he said.