Mills and Bell had two daughters, Juliet, star of television's Nanny and the Professor and Hayley, a Disney child star who appeared in Pollyanna, The Parent Trap and Whistle Down the Wind, and one son, Jonathan Mills, a Screenwriter. In 1947, Mills appeared with his daughters in the film So Well Remembered. The three also appeared together decades later, on an episode of ABC's The Love Boat. Mills's grandson by Hayley, Crispian Mills, is a musician, best known for his work with the raga rock group Kula Shaker.