The incident happened in Addington Street outside Park Plaza hotel at 4.05pm today (March 3).
Officers and London Ambulance Service crews attended, however, the woman was pronounced dead shortly after.
Work is underway to inform her next of kin.
Police enquiries continue, but her death is not being treated as suspicious.
A spokesperson for Metropolitan Police said: “Police were called at 4.05pm on Monday, 3 March following reports a person had fallen from height in Westminster.
“Officers and the London Ambulance Service attended the scene at the Park Plaza on Addington Street.
“Sadly, a 45-year-old woman was pronounced dead at the scene.
“Work is underway in an attempt to inform her next of kin.
“Enquiries continue, but the death is not being treated as suspicious.
“Roads have been reopened.
“A police cordon remains in place.”
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