The essential oil from the dried rhizome of Nardostachys grandiflora, collected from Jaljale, Nepal, was obtained in 1.4% yield, and a total of 72 compounds were identified constituting 93.8% of the essential oil. The rhizome essential oil of N. grandiflora was mostly composed of calarene (9.4%), valerena-4,7(11)-diene (7.1%), nardol A (6.0%), 1(10)-aristolen-9β-ol (11.6%), jatamansone (7.9%), valeranal (5.6%), and cis-valerinic acid (5.7%). The chemical composition of N. grandiflora rhizome oil from Nepal is qualitatively very different than those from Indian, Chinese, and Pakistani Nardostachys essential oils. In this study we have evaluated the chemical composition and biological activities of N. grandiflora from Nepal. Additionally, 1(10)-aristolen-9β-ol was isolated and the structure determined by NMR, and represents the first report of this compound from N. grandiflora. N. grandiflora rhizome oil showed in-vitro antimicrobial activity against Bacillus cereus, Escherichia coli, and Candida albicans (MIC = 156 μg/mL), as well as in-vitro cytotoxic activity on MCF-7 cells.