Hotham began to be involved in politics, and at the 1780 general election he played a major part in the campaign to elect Admiral Keppel at Surrey. Hotham himself contested Southwark, and was returned as Member of Parliament for Surrey at the top of the poll. He did not stand at the 1784 general election but stood at the by-election at Southwark two months later in June 1784. He lost the contest very narrowly. In Parliament he voted with the opposition until the fall of the North government and made two speeches. In 1784 he was a member of the St. Alban's Tavern group who tried to bring Fox and Pitt together.