Bates, 66, who was nominated for best supporting actress in a series, mini-series or motion picture made for TV, for her role in 'American Horror Story: Freak Show', injured herself an hour after the awards got under way at the Beverly Hilton hotel, reported Us magazine.
An onlooker said Bates 'screamed out in pain and almost collapsed before steadying herself on a chair'.
"She limped back to her table and looked to be crying in pain," the eyewitness said, adding that people were en route to tend to the actress.
Earlier she walked the red carpet flashing her cellphone, which was emblazoned with the words 'Je Suis Charlie' - a rally cry honouring the victims of the recent terror attack on satirical magazine Charlie Hebdo's Paris office.