Cary served his apprenticeship as an engraver in London, before setting up his own business in the Strand in 1783.
He soon gained a reputation for his maps and globes, his atlas, The New and Correct English Atlas published in 1787, becoming a standard reference work in England.
In 1794 Cary was commissioned by the Postmaster General to survey England's roads.
This resulted in Cary's New Itinerary (1798), a map of all the major roads in England and Wales.
In his later life he collaborated on geological maps with the geologist William Smith.