Kirkpatrick was state Labor leader from 1917 to 1918, when the party split nationally over Billy Hughes' stance on conscription.

He served as the first president of the National Liberal Reform League in 1883, assisted in forming the United Trades and Labour Council of South Australia in 1884, and served on its parliamentary committee selecting candidates to support prior to the formation of the Labor Party.

[1][4] In 1891, along with David Charleston and Robert Guthrie, he became one of the first Labor members of the Legislative Council, defeating Alexander Hay for his Southern District seat.

He served as Chief Secretary and Minister for Industry in the Price government from 1905 until 1909,[5] when he was appointed the state's Agent-General in London.

He was state leader of the Labor Party from 1917 to 1918 following the 1917 Labor split, and succeeded Crawford Vaughan as Leader of the Opposition when Vaughan's splinter National Party went into coalition with the conservative Liberal Union.