Scholars have not always been sure of Tonson's birthdate, and it has in the past been listed as occurring in 1655 or 1656. But the register of christenings in the parish of St Andrew Holborn demonstrates that Tonson was born on 12 November 1655 and baptized 18 November 1655. The register lists Tonson as the "sonne of Jacob Tonson Shoemaker and of Elizabeth his wife neare Grayes Inn Lane." He is believed to have been related to Major Richard Tonson, who obtained a grant of land in county Cork from Charles II, and whose descendants became Barons Riversdale. His father's will left him and his elder brother Richard, as well as three sisters, each £100, to be paid when they came of age. On 5 June 1670 Jacob was apprenticed to Thomas Basset, a stationer, for eight years. Having been admitted a freeman of the Company of Stationers on 20 December 1677, he began business on his own account, following his brother Richard, who had commenced in 1676, and had published, among other things, Thomas Otway's "Don Carlos". Richard Tonson had a shop within Gray's Inn Gate; Jacob Tonson's shop was for many years at the Judge's Head in Chancery Lane, near Fleet Street.