Documents dating back to 1245, for instance, state that taxes collected from Oos were to be paid to the Lichtenthal Abbey, which was newly founded by Countess Irmengard of Baden.

The Romans under Emperor Trajan had realized the strategic value of the place, a plain at the edge of the Black Forest, and built the military road leading northward from Basel through Oos.

Its strategic value was proven once again in 1634, when the Catholic Margrave Wilhelm of Baden-Baden defeated his Protestant cousin and the Swedish occupying forces in battle on the "Ooser Blutfeld" ("blood plains of Oos"), thus ending foreign rule over his domain during the Thirty Years' War.

The "Europäische Medien- und Event-Akademie" (EurAka) is located in the Cité district, which was formerly inhabited by members of the French occupying forces and their families.

Oos has a fictional resident in the form of Major Grubert, the main character in a series of comics by the French artist Jean Giraud, alias Moebius.