Weston Underwood is a village and civil parish in the unitary authority area of the City of Milton Keynes, Buckinghamshire, England. It is located about a mile west of Olney.
The village name 'Weston' is Anglo Saxon in origin, and means 'western estate', possibly referring to the situation of the village in relation to Olney. The affix 'Underwood' refers to the village's location to a nearby forest, probably the Yardley Chase and Whittlewood Forest.
The parish church of St Lawrence is a Grade I listed building, dating from the 12th to the 15th century.
The hymnodist William Cowper lived in the village from 1786 to 1795.. His name has been given to a number of places there.
On New Year's Eve, 1858, an earthenware vessel was found in "Whites Close" (, near Weston Lodge). It contained 166 denarii from the 1st and 2nd century AD and four Legionary coins. Also found was a complete 2nd century Samian bowl and other pieces of pottery, including many broken sherds, and even human and horse bones. The Samian bowl now resides at Buckinghamshire County Museum.