The A4080 is a British A road which is located on the Island of Anglesey, Wales. The road begins at Menai Bridge and runs via Llanfairpwllgwyngyll, Newborough and Rhosneigr to join the A55 about 9 miles (13 kilometres) from Holyhead. In all the road is about 17 miles (27 kilometres) long. As it is one of the main roads on the island it also forms part of the major bus route of the south of the island. The 42, 4 and 4X routes travel along it, running between Holyhead and Bangor.
Originally the road numbered A4080 ran between Llanwrda and Abermorlain in Carmarthenshire, South Wales. This stretch of road however was re-designated the A40 freeing up the use of the number elsewhere.