Angela Kennedy, 34, lashed out at PC Mark Fleming with her stiletto following a night out with friends.
She struck the officer several times on the face and attempted to hit his colleague after they were called to a disturbance in the town centre of Hamilton, in Lanarkshire.
Police officers had to be assisted by members of the public in restraining the mother-of-one, of Hamilton, by pulling her to the ground.
PC Fleming had to be taken to hospital following the incident in March, where he received stitches to wounds on his face.
At Hamilton Sheriff Court, Kennedy, a first offender, admitted two charges of assaulting the officer and PC Andrew Craig.
Fiscal depute Imran Bashir told the court: "PC Fleming received three stitches to the left hand side of his face. He was given a tetanus vaccination and has been left with some scarring."
Kennedy had not-guilty pleas to charges of assaulting her sister and Kerri Foley and struggling with officers accepted by prosecutors.
Elspeth Forrest, defending Kennedy, said: "She has no recollection of the incident.
"She has a drinking problem and has been attending Alcoholics Anonymous."
Sheriff Joyce Powrie deferred sentence on Kennedy until next month for background reports.
She is on a curfew banning her from leaving her home after 9pm.