<p>It is established that Cr is the passivation-promoting element in stainless steels, and Cr-containing high-entropy alloys (HEAs) have been shown to exhibit passivation. However, despite their high passivation ability, many HEAs exhibit localized corrosion resistance comparable to or even inferior to that of conventional stainless steels. Severe plastic deformation (SPD) is known to significantly improve corrosion resistance in Fe–Cr alloys and stainless steels through ultrafine-grain formation and modification of passive films. This review discusses the influence of SPD on the corrosion behavior of Cr-containing HEAs, with particular focus on the relationship between grain refinement, passive-film stability, and pitting resistance. The review first summarizes corrosion characteristics of HEAs and microstructural evolution during SPD processing. The effects of different SPD routes, including high-pressure torsion (HPT) and shot-blast-based surface-SPD techniques, on the corrosion behavior of representative single-phase HEAs such as CoCrFeMnNi and CoCrFeNi alloys are then discussed. Experimental results indicate that the influence of SPD on corrosion behavior in HEAs is generally smaller than that observed in Fe–Cr alloys. HPT processing mainly improves pitting resistance, whereas surface-SPD methods tend to reduce passive current density. These different responses suggest that the effects of SPD depend strongly on the deformation mode and resulting microstructural heterogeneity. The relatively limited Cr enrichment observed in HPT-processed HEAs compared with UFG Fe–Cr alloys and stainless steels is discussed from the viewpoint of deformation characteristics of HPT and intrinsic nature of HEAs attributed to core effects. The review provides a framework for understanding corrosion behavior in SPD-processed HEAs and suggests future strategies for simultaneously achieving high strength and high corrosion resistance. </p>