In 2007, McKelvie was selected as the SNP candidate for the Hamilton South constituency where she was unsuccessful, however she was elected through the regional list to represent the Central Scotland region. At the 2011 Scottish Parliament election, McKelvie contested the Hamilton, Larkhall and Stonehouse seat and was elected. She served as convener of the European and External Relations Committee from 14 June 2011 until 23 March 2016.[4]
In 2016, she was re-elected to the Hamilton, Larkhall and Stonehouse constituency.[5][6] Within Parliament she became the Convener of the Equalities and Human Rights Committee.
In February 2021 she announced a short medical leave. Her ministerial role was covered by Shirley-Anne Somerville who would fill in as minister for equalities and older people.[7]