Kidd was born Mildred Virginia Kidd in the Germantown district of Philadelphia, Pennsylvania, the youngest daughter of Charles Kidd, a printer, and Zetta Daisy Whorley (both originally Southerners). She had polio at the age of 2, and was paralyzed for a year from the chest down. Kidd discovered science fiction at the age of nine, and became an active science fiction fan: a Futurian and one of the founding members of the Vanguard Amateur Press Association. She married opera singer Jack Emden in 1943 (the marriage lasted until 1947), and then fellow writer James Blish; the latter marriage lasted until 1963.

Kidd successfully worked as a free-lance writer, ghost writer, and proofreader (she was fluent in Latin, French, German, Italian and Spanish). She was an active poet, and published Kinesis, a little magazine devoted to poetry. Her short stories included "Kangaroo Court," published in 1966 in Damon Knight’s Orbit Orbit 1, and later reprinted as "Flowering Season," which was considered by some her best fiction work. She edited or co-edited several science fiction anthologies: Saving Worlds: A Collection of Original Science Fiction Stories (with Roger Elwood, 1973); The Wounded Planet (1974); The Best of Judith Merril (1976); Millennial Women (1978); Interfaces: An Anthology of Speculative Fiction (1980) and Edges: Thirteen New Tales from the Borderlands of the Imagination (1980) (the latter two with client and friend Ursula K. Le Guin).

In 1965, she founded her Virginia Kidd Literary Agency, headquartered at her home, Arrowhead, in Milford, Pennsylvania, and quickly attracted clients from the science fiction community. Her agency was one of the most influential in the field. She withdrew from active management of the agency in the mid-1990s due to complications of diabetes. She died in 2003, but the firm survives her death. She continued to write "in the cracks" (as she put it) throughout her life, publishing her last short story, "Ok, O Che? by K.", in 1995, and her last poem, "Argument," in 1998.