A finite-difference time-domain scheme is proposed for the rigorous study of liquid-crystal photonic and plasmonic structures. The model takes into account the full-tensor liquid-crystal anisotropy as well as the permittivity dispersion of all materials involved. Isotropic materials are modeled via a generalized critical points model, while the dispersion of the liquid-crystal indices is described by Lorentzian terms. The validity of the proposed scheme is verified via a series of examples, ranging from transmission through liquid-crystal waveplates and cholesteric slabs to the plasmonic response of arrays of gold nanostripes with a liquid-crystal overlayer and the dispersive properties of metal–liquid-crystal–metal plasmonic waveguides. Results are directly compared with reference analytical or frequency-domain numerical solutions.