The one-time Green and White Ranger, 35, is in training to become a full-time UFC fighter.
The sixth-degree black belt in karate was inducted into the World Karate Union Hall of Fame in 2003 after developing his own style of fighting called Tose Kune Do.
He says, "I want to prove that I’m a real fighter. I’m not looking for any titles specifically. Ultimately, I want to give my fans something to watch and be proud of."
Frank's decision to become part of the UFC organisation is a positive boost for the Power Rangers franchise after two recent negatives.
Walter Jones, who played the original Black Power Ranger, recently pleaded not guilty to drink driving in Alabama in July 2009 and one-time Power Ranger actor Skylar Deleon, was handed the death penalty after he was convicted in April (09) of murdering an Arizona couple and a California man.