The young women were issued with the fixed penalty notices after police were called to their home in Norwich early on Sunday morning.
The students also face possible disciplinary action from the university.A University of East Anglia spokesperson said: "We fully support the actions of the police. "Students, like everyone else, have to adhere to the law and where there is a breach of the rules they should expect to face the same consequences as others in the community. "We have issued regular reminders about following the rules to all students both on and off campus and in addition to the police action we will also be looking into this matter and taking appropriate action. "In the vast majority of cases our students are behaving responsibly."
Norfolk Police said were tipped off about the party at the address in Bowthorpe Road at about 1.10am.
"Officers found up to 100 people attending a party at the address," said a spokesman for the force.
"Officers dispersed the gathering and three occupants at the address, a 19-year-old woman and two 20-year-old women, were issued with the fixed penalty notice for contravening the ban on being involved in holding a gathering of more than 30 people."
The government has revealed around 9,000 students at nearly 70 universities across England currently have Covid-19. Norwich is reporting an average of around 16 new cases per day, according to government figures.
Additional reporting by Press Association