The three-round fight will be a homecoming of sorts for Cormier, who was an All-American wrestler at Oklahoma State University.
"It feels good to go back to Oklahoma, where I haven't been in almost two years," Cormier told ESPN.com. "I lived there (in Stillwater, Okla.) from 1998-99 until 2010. It's like a second home to me.
"I've got all my people and my family at Oklahoma State. In Oklahoma City I have a lot of great friends. And I have a lot of friends in Dallas, which is a really big place for Oklahoma State graduates.
"I anticipate a pretty decent crowd and a lot of support on my side. So I'm going to go in there and do my thing and Cowboy Up."
Cormier, a native of Lafayette, La., who currently fights out of San Jose, Calif., will take a professional mixed-martial-arts record of 10-0 into the cage against Mir.
During his most recent bout on May 19, Cormier defeated former UFC heavyweight champion Josh Barnett by unanimous decision in a lopsided affair.
That victory earned Cormier the Grand Prix title.
Mir (16-6) becomes the first active UFC fighter to participate in a Strikeforce-promoted bout.
He looks to rebound from a second-round TKO loss on May 26 at the hands of current UFC heavyweight champion Junior dos Santos. Mir is a Las Vegas native and resident.