Nelly Murillo, 18, and her son Yudier Moreno, not yet one year old, were near the site where the Cessna 303 crashed on Saturday in thick brush.
"It's a miracle. It is a very wild area and it was a catastrophic accident," Colonel Hector Carrascal, commander of the Colombian Air Force in Antioquia department, told AFP on Wednesday.
"His mother's spirit must have given him strength to survive."
Murillo and her baby were taken by helicopter to a nearby hospital with minor injuries, said Carrascal, adding that he was stunned they were alive.
"The lady has wounds and minor burns and apparently the child is unharmed," the Colombian air force said in a statement.
The plane's pilot, Captain Carlos Mario Ceballos, died in the crash and rescuers found his body in the aircraft.
A 14-person search-and-rescue team scoured the dense forest before finding the mother and child.
The plane was travelling between Nuqui and Quibdo in western Colombia when it crashed.
Investigators were looking at the cause
Ms Murillo told medical staff that she had managed to open the cabin door and run into the jungle as fire was spreading in the cabin.
She then reportedly went back for her baby, at which time she sustained burns to her face, an arm and a leg.
Afraid the plane might explode, she walked into the jungle along the bank of a small river.
Details of how she survived are still sketchy, but local media said she came across a couple of indigenous people who helped her.
She was also able to drink coconut water from the coconuts the plane had been carrying, local media said.
She reportedly heard the calls over loudspeaker from the rescue helicopter which prompted her to make her way back to the crash site.
She is being treated for her injuries in hospital. Her baby son is said to be unharmed.
