Helen Lydia Mironoff was born in Chiswick, London, to Vasily Petrovich Mironoff and Kathleen 'Kitty' Alexandrina Eva Matilda (née Rogers). Her birth name reflects her dual heritage.

Mirren's paternal grandfather, Pyotr Vasilievich Mironov, was a Russian aristocrat and colonel in the Tsarist army who was stranded in England after a diplomatic mission during the Russian Revolution. Her family's aristocratic past and eventual emigration significantly impacted her family's identity.

Mirren's mother, Kathleen Rogers, came from a working-class family in West Ham, London. Her father was a butcher. This contrast with her father's background highlights the diverse influences in Mirren's upbringing.

The Mironoff family moved to Leigh-on-Sea, Essex, where Helen grew up. Her father, Vasily, anglicized the family name to Mirren in the 1950s, a move that likely reflected a desire for assimilation in post-war Britain.