Llanrhian Mill has two-storeys and is built into the bank, of rubblestone with large, roughly-squared quoins and a half-hipped slate roof. In the centre of the south-west (principal) elevation is a small plaque with the initials I W and the date 1827. This may record the rebuilding of an existing mill on the site, since a mill at Llanhrian is noted in 1557. The south-west elevation had two cart entrances, one of which has been blocked with a modern inserted window. A built-up walkway gives access to the upper floor via a door in the north-west gable.

The mill is reputed to retain a full set of machinery, with an overshot, composite waterwheel at the south-east gable. It was working in 1952, but ceased soon after. The building has been converted to a dwelling, by excavating the bank to the rear and constructing a single-storey lean-to, and with a single-storey extension to the south-west. Against the latter a pair of French burr mill stones were propped in August 2011.

W J Crompton, RCAHMW, 9 July 2014.