Cartier was born in Saint-Antoine, Quebec (then known as Lower Canada). He fought with Louis-Joseph Papineau in the Patriotes Rebellion of 1837, and was forced into temporary exile in Vermont. He practised law when he returned and was elected to the Legislative Assembly of the Province of Canada in 1849. In 1852 he supported the creation of the Grand Trunk Railway, and in 1858 he served as premier of the province. He was a friend of John A. Macdonald, with whom he shared power in the leadership of Canada. In 1864 Cartier and Macdonald joined the Great Coalition with George Brown.
George-Étienne Cartier died in London, England.