Arosa is first mentioned about 1330 as Araus. In 1383 it was mentioned as Orossen and in 1428 it was first mentioned as Arosa.
The first known settlements are from the 13th century. After 1300 Arosa German-speaking Walser settlers came from Davos and replaced the original Romansh-speaking inhabitants. During the following centuries, the village had a subsistence alpine pasture economy. Until 1851 it was politically a part of the Davos municipality. Arosa was established as a health resort by a German doctor in 1883, and the first sanatorium was opened in 1888. From 1900 on it gradually developed as a winter resort. In 1938 the first ski lifts were built, and in 1956 the Weiss horn cable car was opened and further rope and chair lifts followed.
In 1851 Arosa separated from the municipality of Davos.
Skiing in Switzerland received a big boost from Sir Arthur Conan Doyle, author of the Sherlock Holmes series. Conan Doyle, an avid sportsman, was wintering in Davos. For entertainment, he ordered some skiing "boards" from Norway and hiked up the mountain with two local guides. They then skied down into Arosa, ending their journey with a luncheon at a local inn, the Seehof, the first hotel in Arosa. Conan Doyle wrote of his pioneering Davos/Arosa ski adventure in a British magazine, The Strand, in 1894, and the story attracted British skiers to Switzerland.
Erwin Schr�dinger was vacationing in Arosa at Christmas 1926 when he made his breakthrough discovery of wave mechanics.
In 1933, Thomas Mann stayed in Arosa during the first week of his Swiss exile
