[1] Carteret was elected Member of Parliament for Weobly in 1790, a seat he held until 1812, and served as a Lord of the Treasury from 1801 to 1804.
In 1804 he was admitted to the Privy Council and appointed Comptroller of the Household, a post he held until 1812.
In 1826 he succeeded his uncle as second Baron Carteret according to the special remainder and took his seat in the House of Lords.
Lord Carteret survived his wife by two years and died at Dalkeith Palace, Midlothian, in February 1838, aged 68.
He was succeeded in the barony by his younger brother, John Thynne, 3rd Baron Carteret.