Franks grew up in southern California with his father Gerald, his mother Betty and two younger sisters. Although no one in his family played music, his parents loved swing music and his early influences included Peggy Lee, Nat King Cole, Ira Gershwin, Irving Berlin and Johnny Mercer. At age 14 Franks bought his first guitar, a Japanese Marco Polo for $29.95 with six private lessons included - the only music education that he received.
During this time Franks started writing songs, starting with the antiwar musical Anthems in E-flat starring Mark Hamill. He also composed music for the films Count Your Bullets, Cockfighter, and Zandy's Bride, starring Liv Ullmann and Gene Hackman. Sonny Terry and Brownie McGhee recorded three of his songs, including "White Boy Lost in the Blues" on their album Sonny & Brownie. Franks played guitar, banjo and mandolin on the album and joined them in touring. In 1973, he recorded an eponymous album, later reissued as Previously Unavailable, which included the minor hit "Can't Seem to Shake This Rock 'n Roll".
In 1976 Franks released his second album The Art of Tea, saw Franks begin a long relationship with Warner Brothers Music. The Art of Tea featured Joe Sample, Larry Carlton and Wilton Felder of The Crusaders and included the hit song "Popsicle Toes". His third album, Sleeping Gypsy (1977), which includes the song "The Lady Wants to Know", was partially recorded in Brazil. Around this time, percussionist Ray Armando gave Franks a cabasa, which became a signature instrument for him to play on stage when he was not playing guitar. Burchfield Nines (1978), which includes the song "When the Cookie Jar Is Empty", reflects his move to New York City and features more of an East Coast sound. Since then, Franks has recorded more than 15 albums.
His best known works include "When I Give My Love to You", "Popsicle Toes", "Monkey See, Monkey Do", "Lotus Blossom", "Tiger in the Rain", "Rainy Night in Tokyo", and "Tell Me All About It". His biggest hit came in 1983 with "When Sly Calls (Don't Touch That Phone)" from the album Passionfruit. Radio hits include "Your Secret's Safe With Me" from 1985's Skin Dive, and "Island Life" from 1987's The Camera Never Lies.