[1] She represents the electoral district of New Westminster as a member of the British Columbia New Democratic Party (BC NDP).

[3] She then attended Douglas College before enrolling at Simon Fraser University, graduating with a degree in history.

She had worked as a researcher with the Hospital Employees' Union (HEU) in BC, the Canadian Union of Public Employees and the Conseil provincial des affaires sociales in Quebec,[6] before re-joining the HEU in 2015 as secretary-business manager, also covering duties including chief spokesperson and lead negotiator.

[4][7] With incumbent Member of the Legislative Assembly (MLA) for New Westminster Judy Darcy declining to seek re-election in 2020, Whiteside decided to contest the BC NDP nomination for the riding.

[11][12] On December 7, 2022 she was named Minister of Mental Health and Addictions by Premier David Eby.