She was born Jessie Royce Medbury in Chicago, Illinois.
Landis was a stage actress for much of her career. In the 1950s, she began appearing in movies as a character actress, most notably in North By Northwest and To Catch a Thief. She appears in both of these films with Cary Grant. In North By Northwest she plays his mother and in To Catch a Thief she plays Grace Kelly's mother. In real life she was 10 months younger than Grant.
She married three times.
Her autobiography, titled You Won't Be So Pretty (But You'll Know More) was published in 1954.
Landis died of cancer in Danbury, Connecticut.