The two-year-old boy, named in reports as Adam, was discovered lying on the ground in the village of Raclawice, just north of Krakow. He was wearing only pyjamas.
Doctors said on Wednesday he had been brought out of a medically-induced coma and his health was improving.
The boy's grandmother has said she did not see him leave her home.
Police found the boy on Sunday morning lying unconscious near a river, after apparently wandering outside several hours earlier.
The area's temperature had fallen to -7 C (19 F) overnight, the Associated Press reports.
The boy's body temperature was 12 C (54 F) when he arrived at Krakow children's hospital, doctors said, and he was placed in an induced coma.
He was blinking and moving his limbs on Wednesday but was still on a respirator, Janusz Skalski, a heart surgeon at the children's hospital in Krakow, told reporters.
"We're very pleased with his condition... there are no negative symptoms, he's improving," AFP news agency quoted him as saying.
Hypothermia expert Dr Tomasz Darocha told Polish media that until now, the most dramatic case of recovery from hypothermia involved a Scandinavian woman whose body temperature had dropped to 13.7 C.
A toddler is recovering in hospital after being found unconscious in freezing temperatures in Poland.