He married Lady Frances Anne Emily Vane, daughter of Charles William Vane, 3rd Marquess of Londonderry and Lady Frances Anne Emily Vane-Tempest, on 12 July 1843 at St. George's Street, Mayfair, London, England. He died on 5 July 1883 at age 61 at 29 Berkeley Square, Mayfair, London, England, from heart disease. He was buried at Chapel, Blenheim Palace, Woodstock, Oxfordshire, England. His will was probated on 15 September 1883, at above £146,000.
John Winston Spencer-Churchill, 7th Duke of Marlborough was styled as Earl of Sunderland between 1822 and 1840. He was styled as Marquess of Blandford between 1840 and 1857. He held the office of Member of Parliament (M.P.) (Conservative) for Woodstock between 1844 and 1845. He held the office of Member of Parliament (M.P.) (Conservative) for Woodstock between 1847 and 1857. He was awarded the honorary degree of Doctor of Civil Laws (D.C.L.) by Oxford University, Oxford, Oxfordshire, England, on 7 June 1853. He held the office of Lord-Lieutenant of Oxfordshire between 1857 and 1883. He succeeded to the title of 9thEarl of Sunderland [E., 1643] on 1 July 1857. He succeeded to the title of 11th Baron Spencer of Wormleighton [E., 1603] on 1 July 1857. He succeeded to the title of 7th Duke of Marlborough [E., 1702] on 1 July 1857. He succeeded to the title of 7th Marquess of Blandford [E.,1702] on 1 July 1857. He succeeded to the title of 7th Baron Churchillof Sandridge, co. Hertford [E., 1685] on 1 July 1857. He succeeded tothe title of 7th Earl of Marlborough, co. Wilts [E., 1689] on 1 July1857. He held the office of Lord Steward of the Household between 1866and 1867. He was invested as a Privy Counsellor (P.C.) on 10 July 1866. He held the office of Lord President of the Council between March 1867 and December 1868. He was invested as a Knight, Order of the Garter (K.G.) on 23 May 1868. He held the office of Lord-Lieutenant of Ireland between 1876 and 1880, Viceroy. 'His adminstration of Ireland was popular, and he endeavoured to benefitthe trade of the country.'
He began a series of sales of the family collections which was carried on by his successor. In 1875 'the Marlborough Gems' were sold as one lot by Christies for £10,000, the 'the Sunderland Library' realised £60,000; in 1883 'the Blenheim enamels' fetched above £73,000; whilein 1884-85 eleven pictures were sold, with two (Raphael's 'Madonnadegli Ansidei' for £70,000 and Vandyke's 'Equestrian portraits of Charles I' for £17,500) purchased for the nation. Three
Children of John Winston Spencer-Churchill, 7th Duke of Marlborough and Lady Frances Anne Emily Vane