She has been a Labor member of the Australian Capital Territory Legislative Assembly since 2016, representing the electorate of Kurrajong.

Stephen-Smith grew up in O'Connor in Canberra's inner-north[1] and attended local schools such as Lyneham High.

[2] Stephen-Smith previously worked as a senior public servant in the Australian Capital Territory public service, the Department of Prime Minister and Cabinet and as a Chief of Staff to Senator Kim Carr.

[4] Following her election, Stephen-Smith was immediately appointed to cabinet, holding the following portfolios: Community Services and Social Inclusion; Disability, Children and Youth; Aboriginal and Torres Strait Islander Affairs; Multicultural Affairs; and Workplace Safety and Industrial Relations.

[5] After a Cabinet reshuffle in August 2018, Stephen-Smith lost the Multicultural Affairs and Community Services portfolios to new Cabinet member Chris Steel, gaining the Government Services and Procurement and Urban Renewal portfolios.