Zeny Giles was born of a father from Cyprus and a mother from the Greek island of Kastellorizo. After attending Sydney Girls High, she obtained a Bachelor of Arts degree and a Diploma of Education from Sydney University in 1957, a Master of Arts degree in English from the University of Newcastle in 1971, and a Diploma in Special Education from Newcastle College of Advanced Education in 1980. She worked as an English teacher in New South Wales high schools from 1958 to 1962, as a literature tutor with the Workers Education Association (WEA) from 1964 to 1968, as a tutor at the University of Newcastle from 1972 to 1982, and as a part-time remedial reading teacher from 1982. In 1991, Giles was appointed Writer-in-Residence, Migrant Resource Centres Hobart and Launceston and from 1997 through 2003 worked as Creative Writing Tutor at the University of Newcastle.
In 1984 and 1985, her play Zorica was performed to Hunter Valley Schools by Freewheeels, a Theatre in Education Group. In 1989, Miracle of the Waters was highly commended in the Literature and other Writing section of the National Human Rights Awards. In 1998, her libretto for Inside the Storm was performed by the Hunter Singers in the Conservatorium Hall, Newcastle.
Giles has read her work on radio many times, including on Radio ABC in 1989 and Radio 2NUR (Newcastle) in 1990. She read from Miracle of the Waters on Radio National in 1990. She has also read on public occasions including at Carnivale in 1989, at the Von Bertouch Gallery, Newcastle in 1989, at the Darby Street Cafe for International Women's Day in 1990 and during the Greek Writers Conference held at the Royal Melbourne Institute of Technology (RMIT) in February 2000.
Since 2000, Giles has published three collections of poetry, the novel Daughters of Castellorizo, and the poetry / prose / essay collection Caught in the Light : A Celebration of Newcastle, as well as a range of short works.
In 2017, she released the poetry collection Parables, sales from which helped fund the Margaret Henry Memorial Lecture. She remains active in the Newcastle writing scene, including the Newcastle Writers Festival.