Abstract <p>This review article is focused to present an outline of the advancement in the research area of graphene nanostructures such as graphene nanoribbons, graphene nanodisks, graphene nanomesh, graphene nanoplatelets, graphene quantum dots, etc., and their properties in terahertz (THz) region. The density functional theory (DFT) study of graphene nanostructures has also been focused along with their applications in the THz fields such as security, life sciences, analytical sciences, molecular spectroscopy and solid-state physics. The reported study about the graphene nanostructures and their applications have opened up the new gate of opportunities for the fabrication of futuristic graphene based nano-devices. Although a lot of research work has already been reported on the synthesis and the experimental investigation of graphene nanostructures in the literature survey, their computational study using THz spectroscopy is still less explored. That is why in the present article, the theoretical study of graphene nanostructures using DFT in the THz region has mainly been reviewed.</p>