brother of the 2nd Duke of Argyll, and a prominent politician during the early Hanoverian period in Britain.

Campbell served in the army for a short time under the Duke of Marlborough, but he was appointed treasurer of Scotland in 1705 and the following year was one of the commissioners for negotiating the union of the two kingdoms, Scotland and England. Raised to the peerage of Scotland as Earl of Ilay, he was among the 16 Scottish peers chosen to sit in the first Parliament of Great Britain. He became a privy councillor in 1711, keeper of the privy seal of Scotland in 1721, and keeper of the Great Seal of Scotland in 1733. He played an important part in the movement led by Duncan Forbes of Culloden to promote Scottish loyalty to the Hanoverians by raising Highland regiments from among the Whig clans.

Succeeding his brother as duke in 1743, he rebuilt Inveraray castle and collected one of the most valuable private libraries in Great Britain. He died without legitimate issue, and the title descended to his cousin John Campbell, son of John Campbell of Mamore, second son of the 9th Earl of Argyll.