A mother-of-three who vanished almost a week ago has been found inside the roof cavity of a shoe store in Sydney's south.

The family of the 31-year-old Kingsgrove woman said she was last seen at 1.30pm on Friday at shoe store Paul's Warehouse on the Princes Highway at Carlton.

It is understood she was found inside the roof cavity of the store at 12.35pm on Thursday.

A NSW Ambulance spokeswoman said the woman was not trapped and was able to make her own way out where she was treated for dizziness.

She has been taken to St George Hospital where she is in a stable condition.