Officers say the 35-year-old was attacked in Kelvingrove Park at about 21.45pm on Friday, and are looking to speak to anyone who was in the area at the time.
The incident follows two separate sex attacks on women in the city's south side. Last month, a 24-year-old was assaulted in Dixon Avenue, Govanhill, in the early hours of the morning, while a second woman was gang raped a mile away a week before. The man who carried out the most recent assault is thought to have run off in the direction of the city's Western Infirmary.
Det Insp Douglas Robertson, who is in charge of the inquiry, said it was not yet being linked to the previous assaults.
Meanwhile, some 3000 people are planning to take part in a march highlighting sex attacks in the south of the city. The march, These Streets Were Made for Walking, will take place on June 9 at midnight, through the southside.