Moriarty was born in St. Paul, Minnesota, grew up on Cape Cod in Massachusetts and has lived in Northern California since 1966. She attended Sacramento State University and the University of California at Berkeley in the 70s. She was married to the poet Jerry Estrin until his death in 1993, and is currently married to the poet/librarian Nick Robinson.

Moriarty was the Archives Director for the Poetry Center and American Poetry Archives at San Francisco State University from 1986-1997. She received a Poetry Center Book Award in 1984 for Persia. She has also been awarded a Gerbode Foundation grant, a residency at the Foundation Royaumont in France, a New Langton Arts Award in Literature and a grant from the Fund for Poetry. Moriarty has taught at Mills College, and Naropa University, among other places, and is currently deputy director of Small Press Distribution in Berkeley, California.