Ida Lupino was born in Herne Hill, London, to actress Connie O’Shea (also known as Connie Emerald) and music hall comedian Stanley Lupino, a member of the theatrical Lupino family, which included Lupino Lane, a song-and-dance man. Her father, a top name in musical comedy in the UK and a member of a centuries-old theatrical dynasty dating back to Renaissance Italy, encouraged her to perform at an early age.

He built a backyard theatre for Lupino and her sister Rita (1920–2016), who also became an actress and dancer. Lupino wrote her first play at age seven and toured with a travelling theatre company as a child. By the age of ten, Lupino had memorised the leading female roles in each of Shakespeare’s plays.