Martinez started his acting career with the series ''
America's Most Wanted'' in 1993. He has worked in the theater, and a member of
LAByrinth Theater Company. In 2009, Martinez appeared in
Grand Theft Auto IV: The Lost and Damned as Brian Jeremy, the secondary antagonist. In 2010, he appeared in the action comedy
Cop Out as Tino, released on February 26, 2010, by
Warner Bros. Pictures. He portrayed Ginger Goon in the superhero comedy film
Kick-Ass, directed by
Matthew Vaughn and released on April 16, 2010. In 2013, Martinez appeared in the comedy film
The Secret Life of Walter Mitty as Hernando, Mitty's understudy. Later he took a role in
American Hustle as Julius. The film was released on February 27, 2015, by Warner Bros. Focus was his first main role in the career of 20 years, which Martinez likened to "running in a marathon for 20 years and somebody from the side just reached out and handed [him] a cup of Champagne." The film was delayed and eventually released via video-on-demand to poor reviews in 2017. He joined the main cast of the ABC TV series
Stumptown in 2019 as "Tookie", a food truck owner who serves as an informant for the main character, played by
Cobie Smulders. Martinez also stars in the American espionage thriller
The Amateur, which was released in 2025. In 2025, it was announced that Martinez would be joining
Jamie Foxx and
Andrés Baiz in the
Netflix feature film ''
Fight for '84''. == Filmography ==