Police officers discovered the body of the 46-year-old, who has not yet been named, following a call from a member of the public on Wednesday afternoon.
A post mortem examination has not yet been carried out to determine the cause of death but a 46-year-old man has been arrested on suspicion of murder.
A South Yorkshire Police spokeswoman said: "Detectives have launched an investigation following the discovery of a woman’s body in Jordanthorpe.
"A report was received from a member of the public on Wednesday afternoon and officers later attended a flat in Hazlebarrow Crescent, where the 46-year-old woman was found.
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"A post-mortem is due to be carried out to determine the cause of her death.
"A 46-year-old year man has been arrested on suspicion of murder and currently remains in police custody.
"An investigation is now underway."
Anyone with information should call South Yorkshire Police on 101.