Saoirse Ronan's father was born in Manchester, England, and is of Irish origin. Her mother is Irish, and also has small amounts of English and Scottish ancestry.
Saoirse Ronan was born on April 12, 1994, in New York City, New York, the United States, to Irish parents, Monica Ronan (née Brennan) and Paul Ronan, an actor. When Saoirse was three, the family moved back to Dublin, Ireland. Saoirse grew up in Dublin and briefly in County Carlow before moving back to Dublin with her parents.
Ronan spent several years of her childhood living in the Woodlawn section of the Bronx. This neighborhood is composed of predominately Irish and Irish-American community. She holds dual citizenship for Ireland and the United States of America.