The emergency services were called to the blaze at a home on Broomgate shortly after 9pm on Saturday.
Three fire engines were sent to the scene and a 87-year-old woman was taken to hospital.
Police said the woman died later.
A Police Scotland spokeswoman said: “Around 9.15pm, police were called to a report of a fire within a house on Broomgate, Lanark.
“Emergency services attended and an 87-year-old woman was taken to hospital where she later died.
“There are not believed to be any suspicious circumstances and a report will be submitted to the Procurator Fiscal.”