The unnamed woman, who is reported to be 46, was taken to hospital in the city of Pula and is said to be in a stable condition.
She fell from the Norwegian Star cruise ship about 60m off Croatia's coast late on Saturday night.
A Croatian rescue ship was scrambled and found her swimming not far from where she was believed to have fallen.
The woman gave an interview to the Croatia news service HRT after her ordeal, in which she said: "I was in the water for 10 hours, so these wonderful guys rescued me.
The rescue ship's captain, Lovro Oreskovic, said that she was exhausted.
He added that "we were extremely happy for saving a human life".
A Norwegian Cruise Line spokesperson said: "In the morning of 19 August, a guest went overboard as Norwegian Star made her way to Venice.
"The Coast Guard was notified and a search and rescue operation ensued."
More about: #Croatia
