She represented the National Party of Australia in the Australian Senate for the state of New South Wales from 1 July 2005 and served as the Deputy Leader of the Nationals in the Parliament of Australia from 11 February 2016, having previously served as the party's deputy Senate leader since 2008.
In the Turnbull Government, Nash served as the Minister for Local Government and Territories from 19 July 2016, and the Minister for Regional Development, and the Minister for Regional Communications from 18 February 2016 to 27 October 2017.
Nash had previously served as the Minister for Rural Health between 21 September 2015 and 19 July 2016, and as the Assistant Minister for Health in the Abbott Government between 18 September 2013 and 21 September 2015.On 27 October 2017, the High Court of Australia (sitting as the Court of Disputed Returns) found Nash to be ineligible to have been elected, due to holding British citizenship inherited from her father at the time of the 2016 federal election.