Granahan worked at WPTS in Pittston as a radio announcer and disc jockey in his youth. His Elvis Presley-like voice got him a job recording demos of songs submitted to Presley. Granahan was offered a contract with Atlantic Records in 1957 as a rockabilly artist under the name Jerry Grant, but his release sank without a trace, and another release shortly after on Mark Records was also a flop.
In 1958 Granahan teamed with publisher Tommy Volando on Sunbeam Records, and recorded the single "No Chemise Please". The song became a nationwide hit in the U.S., peaking at #23 on the Billboard Hot 100. None of his next four singles for Sunbeam were sales successes; however. During this time Granahan also co-wrote the song "Click Clack" with Dave Alldred of The Rhythm Orchids. A demo of the tune reached Dick Clark, as well as Tony Mammarella, who had just founded Swan Records. Because of contractual obligations, Granahan released the song under the alias Dickie Doo & the Don'ts on Swan, and Clark guaranteed it airplay on American Bandstand. The single's success resulted in Granahan recruiting a backing band consisting of Harvey Davis (bass), Al Ways (sax), Ray Gangi (guitar), and Dave Alldred (drums) to tour and record as Dicky Doo & the Don'ts, who went on to chart several more singles. Granahan also managed a regional hit in the U.S. Northeast with the single "Let the Rumors Fly", released on Gone Records.
Granahan also produced extensively. He recorded the doo wop group The Fireflies and the girl group The Angels, and later in the 1960s, Patty Duke and Jay & the Americans. Granahan produced The Wild Ones' version of the song "Wild Thing", which was dwarfed by the success of the version by The Troggs.