This chapter describes the recent modeling advances made in connection with biomimetic robots made from ionic polymer metal composites (IPMCs). In this context, this chapter describes the initial development of IPMC-based biomimetic robotic fins for robotic fish propulsion, followed by IPMC-based biomimetic robotic jellyfish and then onto biomimetic robotic carnivorous plants and, in particular, the Venus flytraps. A phenomenological model of the underlying sensing and actuation mechanisms in biomimetic robots is then presented, based on linear irreversible thermodynamics with two driving forces—an electric field and a solvent pressure gradient—and two fluxes— electric current density and the ionic solvent flux. Furthermore, a continuum model based on Poisson–Nernst–Planck (PNP) equations is also presented that deals with charge dynamics of cationic migration within the molecular network of IPMCs to generate deformation due to an imposed electric field or generate dynamic output voltage and transient current upon experiencing mechanical deformation, force, torque, strain and stress.