One of the most influential European statesmen of the 1820s, and a friend of William Pitt, he entered British politics as an MP in 1793. He served as Under Secretary at the Foreign Office 1796-9 and joint Paymaster of the forces 1800-1, and as Treasurer of the Navy in Pitt's second ministry.

Foreign Secretary under Portland (1807-9), in manoeuvring to be the latter's successor he attempted to have Castlereagh dismissed, disappointed, he resigned in September 1809 and shortly after was challenged to a duel by Castlereagh and shot in the thigh. This affair prompted his absence from public office for some time, though he undertook a mission to Lisbon in 1812 and re-entered the cabinet (having become reconciled with Lord Castlereagh) in 1816. Canning's real mark on European affairs dates from his appointment as Foreign Secretary in 1822, from which office he succeeded Liverpool as Prime Minister in 1827.

His ministry was not expected to last, having had to rely upon Whig support as some Tories were unwilling to serve under a man whom they disliked; Wellington, for example, resigned as Commander-in-Chief, claiming that Canning had treated him like a dog and even considered calling him out. Canning was Prime Minister for only a few months, worn out with the effort of constructing a government, he never fully recovered from a cold caught at the Duke of York's funeral, and died in August 1827. He had a great reputation as a wit and orator, perhaps his most famous quotation being that concerning his recognition of the independence of the ex-Spanish colonies in South America: “I called the New World into existence to redress the balance of the old.”