He was MP for Liskeard from 1812 to 1818. In 1801 he was appointed Secretary at War in Henry Addington's ministry, transferring to the Home Office in 1803, where he was a strong opponent of concession to the Roman Catholics. He made himself exceedingly unpopular in 1810 by bringing about the exclusion of strangers, including reporters for the press, from the House of Commons under the standing order, which led to the imprisonment of Sir Francis Burdett, 5th Baronet in the Tower and to riots in London. In the same year, Yorke joined Spencer Perceval's government as First Lord of the Admiralty. He retired from public life in 1818.