Two fire engines were called to a maisonette in Earlsfield after a blaze broke out in a kitchen on Tuesday, 19 July.
A neighbour who heard a smoke alarm sounding inside the property in Swaby Road called the Brigade.
London Ambulance Service took a woman to hospital, but she sadly died the following day (Wednesday, 20 July).
Two fire engines from Tooting attended the scene. The Brigade was called at 2115 and the fire was under control at 2141.