Cardenas was born Stephen Antonio Cardenas on May 29, 1974 in Hampton, Virginia, at the Langley Air Force Base. Spending his early childhood as a military brat, Cardenas was raised in San Antonio, Texas. He is of Mexican descent. He started training in martial arts when he was about 12 years old and reached black belt in Taekwondo at age 16. Steve Cardenas has been in martial arts for 28 years. He earned 5th degree black belt in Taekwondo and a black belt in Brazilian Jiu-Jitsu.

After Power Rangers, he owns a martial arts studio in Burbank, California and one in his hometown of San Antonio. In 2009, he started a kids-specific program at Hollywood Brazilian jiu-jitsu studio in West Hollywood, and in 2011 he opened the Force/Balance Brazilian jiu-jitsu & Yoga school. Cardenas had become interested in Brazilian jiu-jitsu after losing a friendly match against “a blue belt in BJJ… [he] choked me out in 10 seconds! He was only training for a year and a half at that time and I had been training for 10 yrs. It was an immediate eye opener.” The style was more difficult for him to learn than other martial arts disciplines.

He holds multiple awards from martial arts contests, including two Silver Medals at Copa Pacifica (2009 and 2011), Gold Medal winner of the 2009 American National Championship, Gold Medal in the 2010 Jujitsu Pro Gear Open, and Silver Medal in the 2010 No-Gi World Championships.

In 2017, he starred in the short movie The Order alongside : Austin St. John, Catherine Sutherland, David Yost, Johnny Yong Bosch, Paul Schrier, Karan Ashley, Walter Emanuel Jones, Erin Cahill, Blake Foster, Nakia Burrise, Hilary Shepard Turner, Dan Southworth, Alyson Sullivan, Deborah Estelle Phillips and Azim Rizk.