Guardino was born on the Lower East Side of Manhattan and raised in Brooklyn, New York. He joined a Police Athletic League dramatic group while attending high school. After graduation, Guardino joined the Navy, serving in World War II.
Guardino's early life took place on the Lower East Side of Manhattan and he was reared in Brooklyn, New York. During his high school years, he joined a Police Athletic League group, which ultimately led to his decision to enlist in the Navy during World War II.