The man, who has not been named, was with a friend on Scales Fell, one of the Blencathra peaks, on Thursday.
The terrain meant an air ambulance was unable to land at the scene, so members of the Keswick mountain rescue team took the decision to carry him to a waiting helicopter.
The man was taken to hospital in Newcastle with severe head injuries.
A spokesman for the rescue team said: "Two walkers on their way down Blencathra spotted something blue on a lower path.
"As they watched, they saw an arm move, and realised to their horror that it was a man in distress.
"One of them got down to him, and realised that he had fallen some considerable distance from the path above, and had suffered serious head injuries.
"A decision was taken to carry the patient down. This was achieved successfully and the casualty was then airlifted to Newcastle's Royal Victoria Infirmary.
A spokesman for the Great North Air Ambulance added: "The helicopter took our doctor and paramedic as close to the scene as was safe, before landing at the base of Scales Fell.
"The patient was assessed and treated before being carried three miles down to the helicopter."
Rescuers carried an injured man for three miles after he fell more than 130ft (40m) down a Cumbrian mountain.