Weather conditions and heavy rain hampered the rescue as the helicopter was unable to fly until first light this morning.
"The area where the man fell was very steep with difficult access," he said.
Mr Brown said police were assisted by Fiordland LandSAR, a local doctor and members of the Milford Sound Emergency Response Team.
"The team went in on foot and medical assistance was provided until a LDART rescue helicopter could fly to the scene."
The climber was flown to Dunedin for treatment. Police do not have information on how far he fell.
The Donne River rises in the Darran Mountains in Fiordland National Park.