The Sirhowy River (Welsh language : Afon Sirhywi) is a river in South Wales and a tributary of the Ebbw River.
The Sirhowy River has its source on the slopes of Cefn Pyllau-duon above Tredegar. After flowing through Siôn-Sieffre's Reservoir it turns south through Tredegar and then Blackwood and Pontllanfraith. It turns eastwards near Cwmfelinfach and joins the River Ebbw near Crosskeys.
Coordinates: 51°40′05″N 3°10′41″W / 51.66806°N 3.17806°W