Henare was born at Pipiwai in the Bay of Islands, in 1878 (probably) or 1877. His father, Henare Wynyard, was said to be the son of Robert Wynyard, acting governor of New Zealand. Henare was initially given the name Taurekareka Wynyard, but later adopted his father's first name as his own surname — this was likely because Robert Wynyard had been active in fighting against Māori, and his grandson, raised as Maori, did not wish to bear his name. Henare was also closely related to a number of prominent figures of Māori history, including Hone Heke. His iwi was Ngā Puhi.
Henare had no formal education in the Western sense, but was taught Māori lore and traditions. He was raised for a time by Wi Pere (later to serve in Parliament) on the East Coast, but later returned north, possibly to avoid an arranged marriage. In 1903, Henare married Hera Paerata, who was half Māori and half Polish.
In the 1914 elections, Henare made his first attempt to win a seat in Parliament. Standing for the conservative Reform Party in the Northern Māori seat, he was successful. He did not often participate in parliamentary debates, but was heavily involved in policy related to Māori interests. He worked closely with Apirana Ngata, a member of the Liberal Party, on a number of important issues, and took part in the consolidation of Māori lands in the North Auckland area.
In World War I, Henare argued against conscription of Māori, and suggested that the return of confiscated lands might persuade Māori to volunteer. He also helped Māori soldiers re-establish themselves upon their return from the war. In the influenza epidemic of 1918, he assisted the delivery of healthcare to Māori. Henare's wife was among the casualties of the epidemic. Henare also played a role in shaping Reform Party policy on Māori issues. He supported the efforts of Gordon Coates, then Minister of Native Affairs, to expand the role of his department, and promoted reforms of the Māori school system.
Henare remained in Parliament until the 1938 elections, when he was defeated by Paraire Karaka Paikea of the Labour Party. Paikea was affiliated with the Labour-aligned Ratana movement, whose rise Henare had opposed.
Henare died in 1940 at his farm near Kawakawa. He was survived by six sons and two daughters. His son, Sir James Henare, was a prominent military officer, and his daughter, Ihapera Taua, was an important figure in the Māori Women's Welfare League. Many years later, his great grandson, also called Tau Henare, was elected to Parliament in the same electorate.