Cary was the son of, a member of the governor’s Council, and Anne Taylor Cary. He was born probably in the mid-1650s at his father’s Warwick County plantation. At the time of his father’s death, Cary was in England, where he remained to complete his education, as his father’s will directed. Sometime during the 1680s Cary married Mary Milner, daughter of Thomas Milner, who was clerk of the House of Burgesses in 1682 and 1684 and Speaker from 1691 to 1693. They had no children before she died on October 27, 1700. In the spring of 1702 Cary married Mary Wilson Roscow, widow of William Roscow, of Warwick County, who had at least three sons from her first marriage. Cary and his rival in the courtship, a violent-tempered captain of an English warship, nearly fought a duel. Cary’s second marriage produced two daughters and two sons.
Cary was a captain in the militia and a justice of the peace for Warwick County by October 21, 1680, but the fragmentary surviving county records do not contain the dates of his appointments. He remained on the county court as late as June 1705 and probably until his death. On June 3, 1699, he became commander of the county militia with the rank of lieutenant colonel.
Cary was elected to the House of Burgesses in November 1682 and again in 1684. Reelected in 1688, he served until 1706 with the exception of the 1695 and 1696 assemblies, to which he failed to win election, and the first part of the autumn session in 1693, which he missed. He became one of the most influential members of the General Assembly. After serving on the Committee of Propositions and Grievances during several sessions and on the Committee for Elections and Privileges in 1691 and 1692, Cary became chair of the latter in the spring of 1693 and that same year chair of the even more important Committee for Public Claims and of the Committee for Proportioning the Public Levy, committees that oversaw most of the important legislation and public spending. He retained the chairs of the Committee for Public Claims and for Proportioning the Public Levy throughout most of the remainder of his tenure in the assembly and from 1699 to 1706 frequently presided when the House resolved itself into a committee of the whole. During those years, only the Speaker wielded more power in the House of Burgesses.
Cary was the senior burgess on a joint committee that from 1699 to 1705 worked on a complete revisal of the colony’s laws, and he was also the senior burgess on a joint subcommittee that oversaw construction of the new Capitol in Williamsburg. His elder brotherwas in charge of that construction. In 1699 and again in 1700 Cary may have been a candidate for Speaker, but the House journals do not identify the unsuccessful burgesses who were nominated for that office.
In addition to being one of the most powerful men in the assembly, Cary acquired other influential and lucrative posts. From October 29, 1691, until December 1692 he was clerk of the General Court. In the autumn of the latter year he traveled to New York to represent Virginia at an intercolonial conference concerning defense against the French. Cary was register of the Virginia Court of Vice Admiralty from early in 1698 until December 27, 1700, and on June 8, 1699, the governor and Council appointed him naval officer, a customs official, for the York River district. He held that office until his death, when the Council took special care in appointing a successor to what its members recognized was “a place of so Considerable a profite.”A founding trustee of the College of William and Mary, Cary served on its board probably until his death and was rector for one-year terms beginning in 1695 and in 1704. The college’s trustees controlled the office of surveyor general of Virginia, to which they appointed Cary in February 1699. He held that lucrative office until his death and for part of the time was also surveyor of Gloucester and York counties. In November 1708 the lieutenant governor included Cary’s name on a list of a dozen men qualified to fill vacancies on the governor’s Council.
Cary had public interests in Elizabeth City and York counties, but he lived in Warwick County, where he eventually controlled nearly 2,000 acres of land and was one of the county’s wealthiest and most influential citizens. Cary died, probably at his plantation in Warwick County, on February 17, 1709, and was buried in the family cemetery there. His widow later married Archibald Blair, a prominent Williamsburg physician and merchant.