Fire crews were called to the Huddersfield property on Monday, February 11.
More in news: Bradford child rapist Michael Cooley jailed for 20 yearsThe pensioner was taken to hospital but has since died from her injuries.
A West Yorkshire Police spokesman said: "Police can confirm a woman has died following a fire at a property in Mirfield.
More in news: Halifax hit-and-run crash leaves teen girls and woman in hospital with serious injuriesThe incident happened on Monday 11 February; officers were called to reports of a fire at an address on Huddersfield Road.
A woman, in her 70s, was taken to hospital, but has since died as a result of the incident."
Investigations are ongoing to establish the exact cause of the fire.