Gabrielle O'Donnell was raised and educated in the Ryde area and completed her tertiary education at Macquarie University. She is a registered psychologist and works as a school counsellor. She is a member of the Australian Guidance and Counselling Association and the NSW Teachers' Federation.

Gabrielle O'Donnell was well known in her electorate when she ran for Parliament. She was first elected to the City of Ryde Council in 1995 and had served on a variety of Council Committees. She was a member of the Sydney North Advisory Committee of the NSW National Parks and Wildlife Service and her campaign leaflet stressed her interest in the environment. In 2005 she was again elected Deputy Mayor of the City of Ryde Council.

Sources used to compile this entry: Ephemera on NSW State and local elections, Box12 , Mitchell Library collection, State Library of NSW, Sydney; http://www.ryde.nsw.gov.au (accessed 10 July 2005); http://pandora.nla.gov.au/pan/33983/20030320/203.17.55.5/Internet/candidate582d.html (accessed 5 June 2005); http://www.emilyslist.org.au/news/editorial.asp?id=163 (accessed 11 July 2005).