Paget succeeded his elder brother Sir Arthur Paget as Member of Parliament for Anglesey in 1807. In 1810 he was appointed a lord of the treasury by Spencer Perceval, a post he retained when Lord Liverpool became prime minister in 1812 after Perceval's assassination. In 1820 he became Member of Parliament for Milborne Port, succeeding another brother, Sir Edward Paget. He continued to represent this constituency and remained a lord of the treasury until in 1826.