Lucy Reis, 20, who was heading to her graduation ball, threw off her shoes and clambered across rocks in her ball gown to reach the youngster.
The girl was unconscious and lying near a pool of water at St Andrews Castle when she found her on Saturday.
Voluntary coastguards who attended the incident praised the student's quick thinking.
Miss Reis, a third year undergraduate art history and psychology student at the University of St Andrews, said: "We were on Castle Sands and there were some other people on the beach and a lot of commotion and people getting upset.
"They were saying that there had been an accident and someone had been hurt.
"I took my shoes off and clambered over the rocks. There was a girl lying on the rocks round the corner near a pool of water. She appeared to be unconscious."
She added: "I don't know first aid but we thought she should be kept still. She was not responding and I checked her head for injuries.
"We were trying to get her to respond which she did after a while. She started to throw up so we turned her onto her side and kept talking to her and asking her name."
Another St Andrews student, Andrew Robbins, who helped Miss Reis comfort the injured girl paid tribute to his fellow student.
Mr Robbins, said: "I'm very glad that we were able to help the girl and her injuries were not worse. But to be clear, Lucy really is owed more of the credit.
"She first suggested that we not move her, she stayed with this girl who we didn't know, and she was extremely calm, helpful and compassionate through everything."
Meanwhile, the St Andrews Coastguard rescue team and a helicopter were alerted and attended the scene.
The injured girl was winched into the rescue helicopter and flown to Ninewells Hospital in Dundee as a precautionary measure.
Joe Mitchell, HM Coastguard senior coastal operations officer, said: "Lucy and Andrew provided vital care in initially ensuring the casualty's breathing was not compromised by the water.
"HM Coastguard are grateful for the time and effort provided by its volunteer rescue teams located around the country who provide this essential rescue capability."
Coastguards have praised a student who ran to the aid of a girl who fell from rocks in St Andrews, Fife.