The first ascent was made on August 7, 1865 by the Bernese mineralogist Edmund von Fellenberg with guides Peter Michel, Peter Egger and Peter Inäbnit. They climbed the mountain from the west side, starting at the Ewigschneefeld, a tributary glacier of the Aletsch Glacier. They successfully reached the summit despite very bad weather conditions. The same climbers had made an attempt on the peak in the previous year, but they could only reach a lower prominence of the Grünegghorn.
A route on the north-east ridge was opened on 26 August 1913 by D. von Bethmann-Hollweg and O. Supersaxo. In the summer of 1950, G. Van der Leck climbed the west face. The western pillar was finally climbed by C. Blum and U. Frei on 27 August 1967.
Famed Swiss mountaineer Erhard Loretan died after a fall on the Grünhorn on 28 April 2011.