Born in St. Louis, Missouri, as Virginia Clara Jones, and tutored by a series of dancing instructors engaged by her aunt, she appeared in the St. Louis Municipal Opera chorus, then appeared with six other girls at an act at the Jefferson Hotel, where she was recruited by Andy Mayo to appear in his popular vaudeville act, as a ringmaster for two men in a horse suit. Virginia assumed the stage name of "Mayo" in the process. She appeared in Vaudeville for three years in the act, appearing with Eddie Cantor on Broadway in 1941's Banjo Eyes.

She continued her career as a dancer, then signed a contract with Samuel Goldwyn and appeared in several of Goldwyn's movies. With Danny Kaye she made some successful comedies, including: Wonder Man (1945), The Kid from Brooklyn (1946) and The Secret Life of Walter Mitty (1947).

In 1949's White Heat she gave one of her greatest performances as Verna Jarrett, the wife of gangster Cody Jarrett (acted by James Cagney). Mayo later claimed in interviews that she was occasionally genuinely frightened by Cagney during the filming of the picture, because Cagney's acting was so realistic and natural.

Also of interest is her role in The Best Years of Our Lives, where she was cast against type and gave a performance that garnered much acclaim.

In 1947, she married actor Michael O'Shea, who died in 1973. They had one child, Mary Catherine O'Shea (born in 1953). The O'Shea family lived for several decades in Thousand Oaks, California.

Through the 1950s and 1960s she ended up getting roles in B-movies, often westerns and adventure films, but also some musicals. Her singing voice was always dubbed.

Mayo got a star on the Walk of Fame for her work in television. It can be found at 1751 Vine Street.

In 1996 she received a star on the St. Louis Walk of Fame.

In the 1990s, Mayo gifted her extensive collection of Hollywood memorabilia to the Thousand Oaks Library. Mayo died in Los Angeles in 2005 from natural causes at the age of 84.