Valeriana vilcabambensis Sylvester & Barrie (Valerianaceae), here described and illustrated, is found as a common constituent of the herbaceous layer in humid, high-elevation montane forests of the Cordilleras Urubamba and Vilcabamba, Peru, which are inaccessible to grazing livestock and the spread of human-induced ground fires. The species is unique in its combination of erect, simple, woody stems to 80 cm tall; pinnate-pinnatisect leaves with elliptic to obovate entire leaflets and usually with a gradually pinnatipartite apex; cymose inflorescence with purpletinged white flowers and purple anthers; and glabrous pappose fruits. A key is provided to help distinguish it from other Peruvian species with cymose or cymosepaniculate inflorescences and pinnate, pinnatisect, or deeply pinnatifid leaves.