Borrowston is a crofting township, comprising about 15 crofts, on the west coast of Lewis, lying on the north shore of Loch Carloway and a half mile west of Carloway. 

The name Borrowston (Borghastan) is from the old Norse "borg" (fortification) and, possibly, "steinn" meaning stone. The "fortification" may refer to the iron age broch which was located on an islet where Carloway pier is now. The pier was built in 1882, although the old curing houses by the pier (now used by Carloway Seafoods) date from the 1840s and were built at the time of Sir James Matheson, landlord of Lewis from 1844 until his death in 1878.

Beyond Borrowston, there is a sizeable peninsula of land known as Laimishader. It is now part of Borrowston Common Grazings, but it was occupied until about the late 18th century, and for much of the 19th century it was part of Linshader tack. When used as a tack, a few families lived there. Laimishader has one of the island's many wells that are dedicated to Celtic saints. This one is called Fuaran Ciaran.

Borrowston has 16 crofts.