The A5025 begins at the A55 road, near Sant Tysilio Nursing Home on the northeastern outskirts of Llanfairpwllgwyngyll.

[1] At Bull Bay, north of the centre of Amlwych, it turns southwest briefly before heading west at Burwen, where it again joins the B5111.

Near Llanfaethlu is briefly turns southeats and then south to Llanfachraeth and Llanynghenedl, before finally heading southwest to the town of Valley, near the Cymyran Strait, where it joins the A5.

The 10-mile (16 km) stretch between Cemaes on the coast and Llanynghenedl in particular has a notorious reputation on the isle for accidents, claiming three lives in just nine months in the late 2000s.

[2] In July 2015 it was announced that several alterations would be made to the road and improvements carried out in anticipation of the (now cancelled) building of a new £8 billion nuclear plant at Wylfa, near Cemaes.