Born and raised in St Petersburg, Russia, Auer moved to the USA after his parents' deaths. He began his career on the stage, working with Eva LeGallienne's acting troupe and later touring the USA with other theatrical groups. While performing on stage in "Magda", he was hired for his first screen role in "Something Always Happens" (1927) and spent the better part of the next decade relegated to playing "foreign" exotics in features like "The Unholy Garden" (1931) and "Sinister Hands" (1932) or playing small, inconsequential roles in support of some of the period's biggest stars like the Barrymore siblings in "Rasputin and the Empress" and Greta Garbo in "Mata Hari" (both 1932).
After his breakthrough turn in "My Man Godfrey", Auer continued to find plentiful work in Hollywood playing wildly humorous supporting roles, often as excitable middle-Europeans. He was genuinely funny in "You Can't Take It With You" (1938) and "Destry Rides Again" (1939) and enlivened "Hellzapoppin'" (1941) and the whodunit "And Then There Were None" (1945). By the late 1940s, however, Auer relocated to Europe where he continued to work until his 1967 fatal heart attack.