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 half 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.

At age 20, Cardenas left his native Texas and settled in Los Angeles to audition for a Mighty Morphin Power Rangers role that would change his life. His character, Rocky DeSantos, replaced Jason Lee Scott (played by Austin St. John) as the Red Ranger in the Mighty Morphin Power Rangers TV series (eventually the Gold Ranger in Zeo), and he later became the Blue Ranger for Power Rangers Zeo. He had no previous acting experience and had to learn on the job. Cardenas left the Power Rangers series and retired from acting during Power Rangers Turbo, due to contract disagreements, and possibly to focus on his martial Artist career. Many years later, starting at the 2007 Power Morphicon convention, he began making convention appearances with other former cast members.

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.