The Dukedom was created in 1702 by Queen Anne; John Churchill, whose wife was a favourite of the Queen, had earlier been made Lord Churchill of Eyemouth in the Scottish peerage (1682), which became extinct with his death, and Earl of Marlborough (1689) by King William III. Anne further honoured Churchill, after his leadership of the victories against the French of 13 August 1704 near the village of Blenheim (German Blindheim) on the Danube River (Battle of Blenheim), by granting him the royal manor of Woodstock, and building him a house at her own expense to be called Blenheim. It was commenced in 1705 and was completed in 1722, the year of his death. Blenheim Palace remains the Marlborough ducal seat.
The first Duke was also honoured with Imperial titles: Emperor Joseph I created him a Prince of the Holy Roman Empire in 1704, and in 1705, he was created Imperial Prince of Mindelheim (once the lordship of the noted soldier Georg von Frundsberg). However, he was obliged to surrender Mindelheim in 1714 by the Treaty of Utrecht, which returned it to Bavaria. According to some sources, he received the principality of Mellenburg in exchange. Regardless, his Imperial titles did not pass to his daughters, so became extinct on his death in 1722.
The Duke of Marlborough holds certain subsidiary titles: Marquess of Blandford (created 1702), Earl of Sunderland (1643), Earl of Marlborough (1689), Baron Spencer of Wormleighton (1603), Baron Churchill of Eyemouth (1682) and Baron Churchill of Sandridge (1685) (all are in the English peerage.) The title Marquess of Blandford is used as the courtesy title for the Duke's eldest son and heir. The Duke's eldest son's eldest son in turn can use the courtesy title Earl of Sunderland.
The later Dukes of Marlborough are descended from the first duke, but not in the male line. Because the first duke had no surviving sons, the title was allowed (by a special Act of Parliament) to pass to his eldest daughter in her own right. A younger daughter, Lady Anne Churchill, married Charles Spencer, 3rd Earl of Sunderland (c. 1674–1722), and from this marriage descend the modern Dukes of Marlborough. They therefore originally bore the surname Spencer. However, George Spencer, the 5th Duke of Marlborough, obtained a Royal Licence to assume and bear the additional surname and arms of his famous ancestor, the 1st Duke of Marlborough, and thus became George Spencer-Churchill. This double-barrelled surname has remained in the family to this day, though some of the most famous members have preferred to style themselves as merely "Churchill".
The Dukedom of Marlborough is the only Dukedom in the United Kingdom that can still pass in the female line. However, the Dukedom does not follow male-preference primogeniture as most other peerages that can pass in the female line do. It actually follows a kind of Semi-Salic Law. The succession for the Dukedom is as follows:
However, it is now very unlikely that the Dukedom will be inherited in the female line again, as all the male heirs of Anne Spencer, Countess of Sunderland – including the line of the Earls Spencer as well as the Spencer-Churchill family – would have to go extinct. If that were to happen, the Churchill titles would pass to the Duke of Bedford as heir-male of Diana Russell, duchess of Bedford, a sister of the third Duke of Marlborough. Should Diana's male issue go extinct, the next in line is the Earl of Jersey, the heir-male of Anne Villiers, Countess of Jersey, daughter of Elizabeth Egerton, Duchess of Bridgwater, a younger daughter of the first Duke.
The present Duke of Marlborough is John George Vanderbilt Spencer-Churchill, 11th Duke of Marlborough.
The title of Earl of Marlborough, which was created for Churchill in 1689, had been created one time previously in British history, for James Ley, in 1626. This title had become extinct in 1679.