Gig Ryan was born in England as her father took the family there for a few years to gain his surgical qualifications (FRCS). They returned to Melbourne in 1957 where Ryan was educated in the Catholic school system. She was interested in reading and writing poetry from an early age, and she won the Victorian 1974 Maryborough Prize, which led to the publication of her first poems.
Ryan has worked at various casual jobs as a waitress, clerk, receptionist and typist. She enrolled in a bachelor of arts program at La Trobe University and in 1974 co-founded the feminist literary journal, Luna. She edited Luna until 1978 when she moved to Sydney looking for a more stimulating poetry and music scene. In 1988 she was awarded a Writer's Fellowship from the Literature Board of the Australia Council which enabled her to complete her first book. In 1988 Ryan won another Writer's Fellowship which enabled her to write full-time and in mid-1990 she returned to the inner city suburbs of Melbourne. In 1993 Ryan graduated with a B.A. degree in Latin and Ancient Greek. She has also been a songwriter and singer with the band 'Driving Past' and, during the eighties in Sydney, performed with the jazz-influenced 'Disband'.
As well as her books of poetry Gig Ryan has published widely in anthologies and a number of journals. She was poetry editor of the Age from 1998 to 2016.