Mallwyd is a small village at the most southern end of the county of Gwynedd, Wales in the valley of the River Dyfi. It lies on the A470 approximately half-way between Dolgellau and Machynlleth, and forms the junction of the A458 towards Welshpool. The nearest village is Dinas Mawddwy, two miles to the north, and Aberangell to the south.