On 10 July 1851, Kingston was sworn in as a member of South Australia's first elected parliament and held his seat in the Legislative Council until 2 February 1857. On 9 March 1857, Kingston was elected to the newly established House of Assembly and became the first Speaker on 22 April 1857. Kingston held this position until 22 March 1860 and again from 31 March 1865 until his death on 26 November 1880. Kingston represented The Burra and Clare from 9 March 1857 to 22 March 1860 and Stanley from 6 May 1861 until his death.