Deputies said the 27-year-old man called 911 at around 2:30 p.m. Thursday and said he was suffering from an unspecified medical issue.
The climber did not fall, according to deputies, and he was thought to be near Timberline Lodge.
Initial efforts to locate him were not successful. As the investigation continued, crews learned he was near the mountain's summit.
A search and rescue team eventually reached the climber, but they determined it was too late to safely bring him down.
An Oregon National Guard Black Hawk helicopter responded to the scene Friday morning, but due to the altitude it was determined a Chinook helicopter would be needed to complete the rescue operation.
That helicopter landed near the scene close to the top of the mountain at around 2:30 p.m. The climber and the search team boarded the helicopter and were brought down to safety.
An update on the climber's condition was not immediately available.