The A4222 follows the original route of the A48 through Cowbridge before heading north along what was the B4270.
The road therefore has two starting points at its southern end, both limited-access GSJs on the A48 either side of Cowbridge. The western section of road runs through the centre of town whilst the eastern section is largely rural; the two sections meet end-on at traffic lights on the eastern side of Cowbridge and the A4222 heads north from here.
Heading away from Brynsadler
The road soon goes under the A48 bypass to pass the local secondary school and enter open country briefly. Aberthin is the next settlement reached, after which the road stays rural for longer. The road climbs to the north to pass through the small village of Maendy and the larger Ystradowen. Continuing across undulating terrain we pass through Talygarn and then go over the M4 to enter Brynsadler.
The road descends to cross the River Ely and then runs through the centre of Pontyclun. It follows Cowbridge Road this side of the railway line and Llantrisant Road on the far side. On the far side of town the road crosses the Afon Clun (presumably on a replacement bridge to the one the town is named after) and then runs through an industrial estate. The road soon ends at a signalised T-junction on the A473 Talbot Green bypass.