She is perhaps best known for starring on the American television series "Nanny and the Professor", which was called an American version of "Mary Poppins". She played Phoebe Figalilly, a nanny with magical powers. Mills has stated that she herself believes in magic, witches and fairies: "There's a lot more, you know, in the aether and around us ... We have guides, and we have angels taking care of us ... I believe in metaphysics, in a big way." She was again nominated for another Golden Globe Award in 1971 for the same role. Despite strong ratings, the series ran only two seasons, in 1970 and 1971. When it moved from a timeslot near "The Partridge Family" and "The Brady Bunch", two hugely successful sitcoms, to a different night of the week, ratings fell eventually leading to its cancellation.