The Semington Brook, a westward-flowing tributary of the Avon,[3] forms the east and north boundaries of the parish.

[4] Semington village developed along the main road from Melksham to Westbury which became the A350 primary route.

It is in the area of Wiltshire Council unitary authority, which is responsible for all significant local government functions.

[1] The Kennet and Avon Canal crosses marshy ground on an embankment on the northern edge of the village.

Just west of the village is the former St George's Hospital, built in 1836–38 as a workhouse for the Melksham poor law union to designs of H. E. Kendall.

[12] Pevsner writes: "It is typical of the coming of the Victorian age how the classical and Grecian motifs get clumsy and extremely heavy".

[12] Today it is largely in residential use, while a charity providing advice to disabled people occupies the ground floor of one building.

Semington was designated as a centre of resistance: extensive anti-tank ditches were constructed to the east, south, and west of the village, these were overlooked by a number of pillboxes.