Falkland was the son of Charles John Cary, 9th Viscount Falkland, and his wife Christiana. He succeeded as tenth Viscount Falkland in 1808 at the age of five after his father was killed in a duel. Falkland was a Scottish reformer and was elected to the House of Lords as a Scottish representative peer in 1831. However, already on May 15, 1832, he was created Baron Hunsdon, of Scutterskelfe in the County of York, in the Peerage of the United Kingdom. This title gave him an automatic seat in the House of Lords. Five years later he was admitted to the Privy Council.
Falkland became Governor of Nova Scotia in 1840 after the recall of Sir Colin Campbell. He opposed the movement led by Joseph Howe for responsible government leading to Howe threatening to horsewhip him. He restructured the colony's Executive Council by including reformers in the body which had previously been a Tory domain but resisted the demand that the majority party in the legislature be permitted to form a government.
Falkland's term ended in 1846. He then returned to England and held office in the Whig government of Lord John Russell as Captain of the Yeomen of the Guard (Deputy Chief Whip in the House of Lords) from 1846 to 1848. The latter year he was appointed Governor of Bombay, in which post he remained until 1853. He returned to England the same year and later served as a magistrate in Yorkshire.
Lord Falkland married Lady Amelia FitzClarence (21 March 1807-2 July 1858 London), the illegitimate daughter of King William IV and his mistress, Dorothy Jordan, on December 27 1830 at the Royal Pavilion. They had one son, Lucius William Charles Frederick Cary, Master of Falkland (24 November 1831-6 August 1871), who married Sarah Christiana Keighly (d. 4 October 1902), but died childless. Lord Falkland died in Montpellier in March 1884, aged 80. As his only son had predeceased him he was succeeded in his titles by his younger brother Admiral Plantagenet Pierrepont Cary.