Prior to her appointment to the Chamber, she was a member of the Legislative Council of New South Wales representing the Liberal Party between 1991 and 2006.

After a period as a public affairs manager from 1987 to 1988, she was Executive Officer to the Minister for Local Government and Planning from 1988 to 1991.

Forsythe is currently a member of the Council of Macquarie University, and serves on the boards of the Hunter Development Corporation, the Hunter Medical Research Institute, Business Events Sydney, the Anglican Board of Mission, and Cricket NSW.

[1] On 1 March 2019 it was announced that Forsythe had been appointed the post of High Commissioner to New Zealand,[4] despite having no previous diplomatic experience and the role being typically held by a career Department of Foreign Affairs officer.

Forsythe was appointed a Member of the Order of Australia in 2019 for significant service to business, and to the people and Parliament of New South Wales.