Savage was born in Australia and first became involved in politics while working in Victoria. He emigrated to New Zealand in 1907. He worked in a variety of jobs, as a miner, flax cutter and storeman, before becoming involved in the union movement. Savage was initially opposed to the formation of the Labour party as he viewed it as not sufficiently socialist enough. Instead he became the chairman of the New Zealand Federation of Labour, known as the Red Feds.
In the 1911 election Savage unsuccessfully stood as the Socialist candidate for Auckland Central. During World War One he opposed conscription, arguing that the conscription of wealth should precede the conscription of men. After the war Savage was elected to Parliament as a Labour candidate. He was one of eight Labour members of parliament and became the party leader following the death of Harry Holland. He helped engineer the Labour/Ratana alliance.
During the depression, Savage toured the country, and became an iconic figure. An excellent speaker, Savage became the most visible politician in the country and led Labour to victory in the 1935 election. The first Labour government swiftly proved popular and easily won the 1938 elections with an increased majority. Savage was suffering from cancer at the time, but had delayed seeking treatment to participate in the election campaign. Savage was to die from this cancer in 1940.
A life long bachelor, Savage brought an almost religious fervour to his politics. This, and his death while in office, has made him become something of an iconic figure to the Left. The architect of the welfare state, his picture was reportedly found in many Labour supporters' homes. While younger generations are less aware of him, he is still revered by many older New Zealanders.