Huntington-Whiteley was born in Plymouth, Devon, the daughter of Fiona (née Jackson), a fitness instructor, and Charles, a chartered surveyor. She has a brother and a sister. She grew up on a farm near Tavistock, Devon. Her paternal great-grandfather, Wing-Commander Eric Huntington-Whiteley JP, was from a recently ennobled family, being the nephew of George Whiteley, 1st Baron Marchamley and the younger son of politician Sir Herbert Huntington-Whiteley, 1st Baronet; Eric's wife, Rosie's great-grandmother, Enid Kohn, was from a family of Polish Jews who emigrated to England in the 1870s. Rosie's paternal grandmother, Gillian, also from a Jewish family, was the daughter of Jacob Franks, a prominent surgeon in Sussex.