Dublin-born Sara Allgood started her acting career in her native country with the famed Abbey Theatre. From there she traveled to the English stage, where she played for many years before making her film debut in 1918. Her warm, open Irish face meant that she spent a lot of time playing Irish mothers, landladies, neighborhood gossips and the like, although she is best remembered for playing Mrs. Morgan, the mother of a family of Welsh miners, in Vadim O Kadar Yeşildi Ki (1941), for which she was nominated for an Academy Award for Best Supporting Actress. Her sister Maire O'Neill was an actress in Ireland, and famed Irish poet William Butler Yeats was a family friend.

Sara Allgood died of a heart attack shortly after making her last film, Sierra (1950).