The climber was in Glen Einich with a fellow student who saw him fall at around 11am yesterday.
His friend ran several miles along a track to raise the alarm at one-and-three-quarter hours later. A search and rescue helicopter form RAF Lossiemouth was called out as was the Cairngorms Mountain Rescue Team.
Willie Anderson, leader of the Cairngorms Mountain Rescue Team, said "There were two young lads were scrambling without ropes or helmets and one of them fell around 200 metres, bounced a few times and sustained head injuries.
"His friend came down to see how he was, sustaining some cuts and bruises on the way.
"But when he got to him he found he was unconscious, although he may actually have been dead by then.
"This second student ran along the landrover track in Glen Einich until he got a signal to raise the alarm. He must have run about five miles by the time I picked him up, which was a pretty good effort given he was injured himself."
Mr Anderson said there was not an issue with them not having ropes or helmets as plenty of climbers scrambled without them.
"It was just one of those accidents that happen in the hill," he said. "In fact I am going to write to the young guy who survived.
"I feel so sorry for him witnessing that happening to his mate. I want just to underline he was absolutely blameless."
He said had the body had been recovered by helicopter.
It is understood the two students had come from the south of England and had been camping in the area.
It was the third time this week that the Cairngorms team had to help injured climbers. One male sustained a broken leg in Glen Feshie while a woman broke her collarbone in the Monadhliath Mountains.
Police said they were carrying out inquiries into the incident Glen Einich and there was no further information at this time.
In a statement, they said: "The man will not be identified until all next-of-kin have been informed and a report will be submitted to the Procurator Fiscal."
Another climber was recovering yesterday after plunging 300ft down a Highland mountain.
The man was on Stac Pollaidh, north of Ullapool, Wester Ross, when he lost his footing.
Dundonnell Mountain Rescue Team leader Mick Holmes said they received a call from the police at about 1.30pm on Thursday and called Rescue 100, the Coastguard search and rescue helicopter based in Stornoway. The man was airlifted to Raigmore Hospital.