Winston Leonard Spencer-Churchill was born on 30 November 1874. He was an heir of a noble family of the Dukes of Marlborough. His ancestor George Spencer, a member of the aristocratic Spencer family, was proud of his consanguinity with John Churchill, 1st Duke of Marlborough, so he has decided to choose Spencer-Churchill as his surname when he took the title of Duke of Marlborough in 1817.

Winston Churchill's father, Lord Randolph Churchill was a politician and the third son of John Spencer-Churchill, 7th Duke of Marlborough. Following the example of his father, Winston preferred to be known as Churchill. His mother was also born in a respected family, being a daughter of Leonard Jerome, a millionaire from the USA. Lady Randolph Churchill, gave birth to her son in Blenheim Palace, Woodstock, Oxfordshire, two months before the expected date.

When Winston was a kid, his grandfather had been appointed Viceroy, and Winston's father, Lord Randolph, was hired as his private secretary. At that time the family had lived in Dublin and had used to stay there until Winston turned six. Dublin is also a birthplace of his younger brother John Strange Spencer-Churchill. Those years in Ireland are considered to be very important for the formation of the character of the future Prime minister because frequent parades by the Vice Regal Lodge (now the official residence of the President of Ireland) were the probable reason of his passion towards military matters.