Courmayeur's popularity initially derived from its celebrated thermal spas – the town has four sources of sulphur-rich water that came into vogue in the 18th century. In the late 19th century, the Mont Blanc massif started to be explored and studied with a view to finding a way to reach the summit of the eponymous mountain.
After several reconnaissance attempts on the part of the Genevese mountaineer and naturalist Horace-Bénédict de Saussure, together with his guide Jean-Laurent Jordaney, who was originally from Pré-Saint-Didier, the first ascent was completed in 1786 from the French side, in the company of guides Michel Paccard and Jacques Balmat of Chamonix.
Indeed, together with Chamonix, Courmayeur subsequently became the capital of global mountaineering, and was the site of the establishment of the first company of Italian mountain guides, the so-called Società Guide Alpine di Courmayeur (or the "Société des guides de Courmayeur" to give it its French name) in 1850. Courmayeur is one of the historic centres of mountaineering in the Val d'Aosta, together with Breuil-Cervinia and Champoluc.
During the 19th century, royals would stay regularly in Courmayeur. Starting in the 20th century, with the construction of the first ski facilities, it became one of the leading ski resorts in the Alps.