Vesti FM radio said the girl, Julia, disappeared with her pet dog from Pierzwin village in Lubusz province in Poland Friday. She was found lying in a nearby marshland Saturday with the dog by her side.
Firefighters who found the girl said the dog kept the child warm enough throughout the night, with temperatures plunging to minus five degrees Celsius.
More than 250 firefighters, police officers, rescue workers and residents searched for the child throughout the night.
They also employed a police helicopter with infrared cameras and six search dogs to look for the girl.
Julia was taken to a hospital where she is recovering. She appears to have suffered some frostbite but her health condition is not life-threatening, the hospital said.