The young girl, believed to be about 5, was playing in the water off the Greek coast when she was swept more than 800m from shore.
When her panicked mum and dad realised she had drifted out to sea, they called the local ferry asking if they could help rescue her.
The ferry, which was performing its regular route, approached her and captain Grigoris Karnesis positioned the vessel so the current gently pushed the girl, who was wearing inflatable arm floaties but no life jacket, toward it.
Crew members then plucked the girl and the blow up floating unicorn from the water and reunited her with her worried parents.
The incident took place on Sunday in the sea area off the town of Antirio in the Gulf of Corith.
"The child was flabbergasted," he told Skai TV.
"She was terrified, and that is why she had grabbed so firmly onto her inflatable swing ring."
He brushed off suggestions he had done anything noteworthy, saying he only did what anyone would do.
"I'm obligated to do it, not because of the nature of my work, but as a person," he said.
"There is no need for someone to thank me.
"I did something that any one of us would do."
