Jack Grimes was born in Manhattan. His career in acting began at age seven, during the depression, when Jack was forced to find work in order to help earn money for his family.
Jack went on to get work in radio beginning with the CBS program, "Let's Pretend." He was also cast in "Fred Allen", "The Phillip Morris Playhouse", "Second Husband", and "Death Valley Days." By age 12 Jack was doing 35 to 40 radio shows a week. In 1944, Jack commuted to California to act in films for Universal Pictures.
Grimes also voiced Jimmy Olsen in the last three years of The Adventures of Superman radio program, and the Filmation TV series The New Adventures of Superman.