A scholarship that Landis received when she was 14 enabled her to attend the Hinshaw Dramatic School, which led to her acting two years later with the Evanston Stock Company.

When her first husband's family encountered financial problems, she joined the North Shore Players as leading lady and director.

[9] In the 1950s, she began appearing in movies as a character actress, such as her roles in To Catch a Thief (1955), and North by Northwest (1959), both starring Cary Grant and directed by Alfred Hitchcock.

Landis's appearance in North by Northwest earned her publicity for portraying Cary Grant's mother despite claiming to be nearly a year younger.

Landis made many television appearances in programs such as The United States Steel Hour, Alfred Hitchcock Presents, and Boris Karloff's Thriller.

In 1956, she married her third husband and widower,[2] United States Army Major General John F. R. "Jeff" Seitz (died 1978).