He began climbing with Reinhold Messner in 1969. Several accomplishments in mountaineering followed. The most notable event was the first ascent without supplemental oxygen of Mount Everest on 8 May 1978 together with Messner, which was previously thought to be impossible. A year after his climb on Everest he published Lonely Victory (Der einsame Sieg. Autor: Eberhard Fuchs) in 1978. Habeler set further records by descending from the summit to the South Col in only one hour and climbing the North Face of the Eiger in ten hours.