The woman was treated by paramedics at the home in Cornwall Close, Hornchurch, but died at the scene on Monday afternoon.
The two dogs were seized by armed officers after being contained in a room.
It is believed to be the first fatal attack by XL bully dogs that were known to have been registered under new laws.
A blue forensic tent was put up outside the woman's home in the small residential street following the attack.
The family of the woman, who was the owner of the dogs, is being supported by officers, the Metropolitan Police says.
Neighbours have described seeing paramedics administer CPR to the victim in her front garden.
Comment: On the same day in another part of the country just to the south of Faryab province: Flood again wreaks havoc in Afghanistan, another 50 killed in Gor province