Westonbirt House is a country house in Gloucestershire, England, about 3 miles (5 km) southwest of the town of Tetbury. It belonged to the Holford family from 1665 until 1926. The first house on the site was an Elizabethan manor house. The Holfords replaced it first with a Georgian house, and then Robert Stayner Holford, who inherited Westonbirt in 1839, replaced that house between 1863 and 1870 with the present mansion which was designed by Lewis Vulliamy. He also remodelled the gardens, diverted the main road and relocated the villagers.

Robert Stayner Holford (1808–1892), of Westonbirt, in the village of Weston Birt, Gloucestershire, MP for East Gloucestershire, was a wealthy landowner, gardening and landscaping enthusiast, and an art collector. With his vast wealth, he rebuilt Westonbirt House from the Georgian mansion erected only decades earlier by his father, and founded the Westonbirt Arboretum after succeeding his uncle and father between 1838 and 1839. His London home was Dorchester House.