The dispersive properties of liquid-crystal-tunable metal–insulator–metal plasmonic waveguides are theoretically investigated as a function of the applied control voltage. The LC reorientation study is rigorously coupled to the optical studies via a multiphysics finite-element analysis. A Bragg grating resonator is designed based on the proposed waveguide, which shows an extensive tuning efficiency of more than 100 nm V− 1 for low operating voltages up to 2 V.