South Yorkshire Police said the 43-year-old was mugged as she walked along Cliffefield Road, Swinton, at around 12.10am on Sunday, August 27.
Cash and cigarettes were stolen during the mugging.
A South Yorkshire Police spokeswoman said: "It is reported that a 43-year-old woman was walking along Cliffefield Road, Swinton, before it is believed she was assaulted and robbed of some cash and cigarettes, by offenders unknown.
"The woman sustained serious facial injuries during the incident which required hospital treatment."
Anyone with information should call South Yorkshire Police on 101.