Born in England, Cook became a coalminer; after coming to New South Wales in 1886 he found work at Lithgow mines.

He became secretary of the Miners' Association and won the seat of Hartley for the Labor Leagues in 1891. His association with the Labor Party was short-lived and he aligned himself with the Free Trade group of George Reid in the New South Wales parliament and then in the federal parliament, to which he was elected as the member for Parramatta in 1901.

He joined the first federal parliament in 1901 as a Free Trade member and, despite being described as having 'no glow', held the federal seat of Parramatta for 20 years.In 1908 Cook became leader of the Free Trade Party and combined with Alfred Deakin and the Liberal Party to form the anti-Labor Fusion government in 1909. In 1913 Cook replaced Deakin as Liberal leader and his party gained a slim majority in the election of that year.Cook's term as prime minister was short as his legislative progamme was frustrated by the Labor-controlled Senate, leading him to gamble on an early election in 1914 which he lost.

From 1917-1920 he was minister for the navy in Hughes' Nationalist government and represented Australia at the Versailles Peace Conference in 1919. He was treasurer in 1920-21 and then retired from politics. From 1921 to 1927 he was Australia's high commissioner to London.

He was knighted in 1918. Joseph Cook was 31 in 1891 when he became Labor member for Hartley in the New South Wales parliament. Three years later, he was a minister in George Reid's Free Trade government.

A man of great determination, he was quick to make the most of two major re-alignments of political parties in the parliament's first two decades.In 1909 he became Defence Minister, after taking a key role in the fusion of non-Labor parties that year.In 1917, he led the Liberal Party in a merger to form the Nationalist Party and served as Navy Minister and as Treasurer in WM Hughes' government. Joseph Cook was Australia's sixth Prime Minister, taking office in 1913 with a Liberal Party majority of only one seat in the House of Representatives.

On leaving politics, Cook served as Australia's third High Commissioner in London from 1921 to 1927.