A 27-year-old man has been winched to safety after spending Saturday night stuck on a rock ledge in the Royal National Park south of Sydney.

Inspector Jason Rutherford from NSW Ambulance said the hiker was walking along the rocks yesterday before he was swept into the water.

Mr Rutherford said the man climbed back onto the rocks and up a cliff face but was unable to climb any further.

He said the hiker stayed there for the rest of the evening before he was able to alert people walking nearby at around 10:30am on Sunday.

"The information I have from the patient was that he ended up in the water yesterday and he was swept onto the rocks," Mr Rutherford said.

"Today, he caught the attention of workers in the area of Eagle Rock who alerted emergency services."

The man had suffered mild hypothermia and scratches but was conscious and breathing when he was found.

Paramedics from the Specialist Operations Team abseiled down the steep cliff face to reach the man on the rock ledge so he could be assessed and treated before being winched out by a helicopter.

"It was a difficult expectation from where the patient was located," Inspector Rutherford said.

"He was unable to be winched or lifted so they set up a safety system to moving sidewalks to a place where it would be safer."

The man was taken to Sutherland Hospital in a stable condition.