In 1946 she married and divorced George Weidler. Her 1951 marriage to third husband, Marty Melcher, appeared to be tranquil on the surface, but after he died in 1968, she discovered that, as her agent, he had mismanaged her finances as well as her career, leaving her bankrupt and without any prospects of work.

In 1974 she was awarded $22.8 million in a suit against her former lawyer and manger, Jerome B. Rosenthal, for malpractice in handling her affairs. She eventually settled for $6 million. Her fourth marriage, to Barry Comden, lasted from 1976 to 1981.

An activist in animal rights, Day currently runs the Doris Day Animal Foundation in Carmel, California, which advocates the proper care of pets.