Ceratozamia guatemalensis, a new cycad species from the Sierra de los Cuchumatanes, Huehuetenango, Guatemala, is described and compared with the geographically proximal congeners C. vovidesii and C. matudae, with which C. guatemalensis has been historically confused based on their pendulous seed cones, a rare trait in the genus. Nonetheless, a recent phylogenetic study suggests that C. guatemalensis and C. vovidesii are sister species, while C. matudae belongs to distant clade. The new taxon is easily distinguishable from both C. vovidesii and C. matudae by qualitative and quantitative traits based on vegetative and reproductive structures. Remarkably, C. guatemalensis is characterized by having significant morphometric differences from the other two species, such as the wider median leaflets and wider leaflet articulations, and qualitative traits such as the seed cones of green color. The description of C. guatemalensis represents the recognition of the first endemic Ceratozamia species from Guatemala. It should be considered Critically Endangered (CR) due to limited populations and the ongoing destruction of its habitat.