The Yellow River rises in Kilcorbry, north of Croghan (near 53.351°N 7.302°W) and flows in an easterly direction.

It passes under the R400 and then turns northeast, flowing under Garr Bridge[2] It meets several tributaries and then its last section forms part of the Meath–Offaly border and passes under Sheep Bridge south of Castlejordan.

[3] It meets the Monagh River and then passes under Clongall Bridge[4] and later enters the Boyne near 53.3818°N 7.0816°W.

From the tripoint of the townlands Stonehouse, Killowen (both in County Offaly) and Ballyfore (County Meath) (53.3956°N 7.1421°W) until the junction with the River Boyne the Yellow River forms the boundary of counties Offaly and Meath.

The Yellow River is known as a brown trout fishery.