Winfield House is an English Neo-Georgian townhouse located in Regent's Park, central London. It serves as the official residence of the United States Ambassador to the United Kingdom. The property spans 12 acres, making it home to the second largest private garden in London after Buckingham Palace. The house was originally built for American heiress Barbara Woolworth Hutton in 1936 on the site of a previous villa that was damaged by fire. Hutton named the house after her grandfather Frank Winfield Woolworth. During World War II, the house was used by the Royal Air Force, and after the war, Hutton donated it to the U.S. government, which has used it as the ambassador's residence since 1955. The house is Grade II listed for its architectural and historical significance.

The grounds include a large front wood, sculpture garden, formal garden, vegetable garden, tennis court with greenhouse, and extensive lawns for entertaining. The house has undergone renovations and interior redesigns over the years, including notable alterations in 1969 by designer William Haines.

Winfield House has hosted numerous dignitaries and events, including U.S. presidents and important diplomatic functions, reflecting its role as a hub of diplomatic hospitality.

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