In her time at Catherine House, she oversaw the implementation of National Disability Insurance Scheme funding at the non-profit.

[5] On 10 March 2020, she became chief executive of St Vincent de Paul Society SA as the COVID-19 pandemic hit.

Miller-Frost was critical of the Marshall government's plans, and expressed a desire for more social housing in the state.

[9] Miller-Frost was preselected by the Australian Labor Party to run for Parliament in the seat of Boothby in the 2022 federal election.

[8] Incumbent Nicolle Flint chose not to run for re-election citing a toxic workplace in her valedictory speech, meaning Miller-Frost's main opponents were Rachel Swift from the Liberal Party, and independent candidate Jo Dyer.