Educated at home, John completed a grand tour of Europe when he was 19.
Russell entered politics in 1732, and was preparing to run for Parliament when his brother died and he became the fourth Duke of Bedford.
After Walpole retired, Henry Pelham formed his ministry. John Carteret attempted to draw Bedford into government. In December 1744, Bedford became First Lord of the Admiralty and a member of the Privy Council in the process. In 1745 he became Lord Justice of Great Britain, colonel of a regiment raised to oppose the Jacobite rebellion of 1745. He also served in many other administrative posts.
Bedford became secretary of state for the Southern Department in February 1748 (1747, under the old calendar) and held that position until 13 June 1751. He resigned because he was constantly in conflict with the Duke of Newcastle, Henry Pelham’s brother, in the Pelham administration. Although he was not particularly hostile to the Pelham administration, he could not be persuaded by Henry Fox, who became secretary of state for the Southern Department in 1755, to rejoin the government, although many of his close political friends did so. Nevertheless, he became lord lieutenant of Ireland in 1757. He remained in that post until 1761, dealing with serious riots in Dublin in 1759 and 1760 (when it appeared that there might be a legislative union between England and Ireland), and deterring a French expedition in February 1760 that aimed to help the rebellion.
On retiring from office, he joined Lord Bute in seeking a speedy conclusion to the Seven Years’ War (1756 to 1763) with France. He remained controversially connected with British politics; he was strongly opposed to the repeal of the Stamp Act, and he demanded that the American colonists accept the will of the British government. He refused many offers of government posts, and by the beginning of the 1770s was withdrawing from politics. He died on 15 January 1771.
In the House of Lords he became a strong opponent of Sir Robert Walpole, supporting the position of the Tory group led by John Carteret. He was also opposed to the presence of 16,000 Hanoverian troops in British pay.
He married Lady Diana Spencer, the daughter of the third Earl of Sunderland and sister of Charles, third Duke of Marlborough, in 1731. After Lady Diana died in 1733, he married Gertrude Leveson-Gower, daughter of John, Earl Gower, in 1737.