In 1878 he was elected to the Tasmanian House of Assembly, becoming Attorney General in 1887. It was after a visit to the United States in 1890 that Andrew Inglis Clark became a committed 'republican' which subsequently led to his passionate involvement in the Federation of Australia.
In 1896, after several failed attempts he was able to get a system of proportional representation adopted by the Tasmanian Parliament:- see Single transferable vote.
Clark, never in robust health, in fact described as "small, spare and nervous" by Alfred Deakin, died on November 14, 1907. He is buried in the old Queenborough Cemetery at Sandy Bay.