North Wales Police said a Citroen C1 car crashed on junction 24 near Abergele at 07:30 GMT on Thursday.
The 31-year-old woman was taken to hospital but has since died.
Police are investigating and are keen to speak to the driver of a silver Ford Focus that may have witnessed the collision. Witnesses have been asked to contact police on 101.
A woman has died following a collision on the A55 in Conwy county.