Kaiseraugst (Swiss German: Chhäiseraugscht) is a municipality in the district of Rheinfelden in the canton of Aargau in Switzerland. Located on the High Rhine , it is part of the Basel metropolitan region and borders Germany and the canton of Basel-Landschaft . It is named after the Ancient Roman city of Augusta Raurica whose ruins are nearby. The prefix Kaiser- ("imperial") refers to the fact that from medieval times the town formed part of the Habsburg territory of Further Austria, as opposed to the neighbouring village of Augst , which was part of the Canton of Basel in the Old Swiss Confederacy.

Founded as a Roman fort, Castrum Rauracense, around AD 300, Kaiseraugst has a rich history tied to its strategic position along the Rhine. Today, it is one of the fastest-growing residential and industrial centers in the region, hosting major companies like Hoffmann-La Roche.