Audrey Thom, 58, from Fife, was badly injured in the accident on the A914 between Dairsie Roundabout and Balmullo on Tuesday.
Mrs Thom was a passenger in a grey Mazda 3 when it was involved in a collision with a white Renault Traffic van.
Mrs Thom died on Thursday. The van driver suffered minor injuries.
Police are appealing for witnesses.
Her family said: "Audrey was a much loved wife, mother to three daughters and very recent granny. She will be sadly missed."
Insp Brenda Sinclair, of Police Scotland, said: "We are still making inquiries to establish the full circumstances of this collision.
"We are asking anyone who was in the area at the time and saw these vehicles or who witnessed the collision, to contact us."
A woman has died in hospital two days after a crash involving a car and a van in Fife.