Ehrenbreitstein Fortress (German: Festung Ehrenbreitstein) is a fortress on the mountain of the same name on the east bank of the Rhine opposite the town of Koblenz in the German state of Rhineland-Palatinate.

Occupying the position of an earlier fortress destroyed by the French in 1801, it was built as the backbone of the regional fortification system, Festung Koblenz, by Prussia between 1817 and 1828 and guarded the middle Rhine region, an area that had been invaded by French troops repeatedly before. The Prussian fortress was never attacked.