[1] The name Gwenfro is possibly derived from the Welsh language words gwen (feminine of gwyn), "white", and bro, "border", "boundary".

The river rises at a number of small springs south and east of the village of Bwlchgwyn, including a place called Ffynnon y Ceirw ("spring of the stags").

It flows eastwards for several miles through a rather deep valley, and is joined by several other streams; it then passes through Wrexham city centre, where it is largely culverted, and joins the Clywedog at King's Mills.

[3] The Gwenfro was an important water source for Wrexham industry and has had pollution issues.

Although still periodically affected – an incident in 2006 led to a fine for Welsh Water – fish including brown trout and roach are now present.