The son of a real estate executive, Martin moved to Garden Grove, California, as a child, where he worked at Disneyland during his teens. At Disneyland, he entertained crowds with magic tricks and later with banjo music and comedy. He eventually studied theater arts at UCLA and broke into show business as a comedy writer. In 1969, he won an Emmy for his writing on the hit comedy show The Smothers Brothers and later wrote and appeared on other comedy-variety shows, including The Sonny and Cher Comedy Hour.
Meanwhile, Martin began performing his own comedy at nightclubs and on records. He was soon guest-hosting The Tonight Show and appearing on Saturday Night Live, notably in the role of the "wild and crazy guy."