Vaccinium shastense J. K. Nelson & L. Lindstrand III (Ericaceae) is described as a new species from interior California. This new species is most similar to V. parvifolium Smith but differs by its ciliate, inrolled leaf margins, much wider hypanthium scar, dark blue, glaucous, quickly deciduous fruits, greater seed count, and pitted seed surface sculpturing. Moreover, V. shastense and V. parvifolium are allopatric, occur in distinct habitats, and have distinct genetic characters. Two subspecies of Vaccinium shastense are described: Vaccinium shastense subsp. shastense, endemic to the southeastern Klamath Mountains in Shasta County, California, and Vaccinium shastense subsp. nevadense J. K. Nelson & L. Lindstrand III from the western slope of the Sierra Nevada, California. The new subspecies differ from one another in flower color, length of persistent calyx ring, growth habit, geographic range and habitat, and distinct genetic characters. Vaccinium shastense subsp. shastense and Vaccinium shastense subsp. nevadense are compared to morphologically similar taxa in California by inclusion of an updated species key.