 Hamilton was returned as MP for Lanarkshire at a by-election on 23 December 1718.He retained his seat at the 1722 British general election , with the help of his 19-year-old nephew, the 5th Duke of Hamilton, a Tory who was actually on the opposing side politically.He was returned again unopposed for Lanarkshire at the 1727 British general election and joined the Board of Admiralty under the Walpole–Townshend ministry in May 1729.