Farnworth is a town in the borough of Bolton in England. It lies on the River Irwell and the River Croal and has a population of around 25,000 people.

The town grew up in the eighteenth and nineteenth centuries around the coal mining industry. Other industry included iron foundries and cotton mills.

Farnworth has a market and a theatre, and is also known for its underground canals , running from the mines to Worsley.