The US cycling star, who rode in last year's event, will be joined by Team RadioShack teammates Levi Leipheimer, the defending champion of the Tour of the Gila, and Jason McCartney.
The professionals will compete independently of Team RadioShack because rules ban elite-level teams from national level events such as the Gila.
Armstrong will wear the outfit of Mellow Johnny's bike shop from his hometown of Austin, Texas.
Two weeks ago, Armstrong pulled out of the four-day Circuit de la Sarthe because of a stomach illness.
Armstrong also plans to ride in the Tour of California before returning to Europe in June.