From its source to the confluence with the River Parrett, it is about 33km long and falls 370m. The River originates at Beverton Pond in the Parish of Huish Champflower in the Brendon Hills to the southwest of the county. From this point the river flows southeast through a wooded narrow valley into Clatworthy reservoir, constructed between 1957 and 1959 and officially opened in 1961. From the reservoir the river flows south past the settlement of Huish Champflower. The river continues south within a steep sided wooded valley through Waterrow and then southeast through the parish of Ashbrittle.
The course of the river demarcates the county border on the west side of the Parish of Stawley before turning north to run through the village of Greenham and past Cothay Manor. At Lutley Bridge, Stawley Parish, the river's course turns to the southeast through Langford Budville Parish and then northeast, past Tone and northeast through Nynehead Parish to Bradford-on-Tone. The river continues northeast to Bishops Hull Parish and then east to run through the centre of Taunton where the channel has been extensively straightened.
The river continues east to the north of Ruishton and south of Creech St Michael and through Creech where it then passes through the wetland of West Moor, Curry Moor, Hay Moor and Hook Moor to Curload in Stoke St Gregory Parish. The river continues northeast through Stan Moor and past Athelney in the parish of Burrowbridge. The River Tone joins the main channel of the River Parrett at Burrowbridge, in land to the south of the Polden Hills. The Tone is tidal up to the Newbridge Sluice in North Curry Parish.