<p>Flexoelectricity represents a higher-order electromechanical coupling phenomenon whereby strain gradients within a material can induce electric polarization. Flexoelectricity is observed in hard dielectric ceramics as well as a wide range of soft matter. This contribution establishes a rigorous and comprehensive framework for finite-deformation flexoelectricity in generalized Toupin’s electroelasticity. Following the variational principle, we present the equilibrium equations, boundary conditions, and constitutive relations for nonlinear flexoelectricity. The existing theory of flexoelectricity at small deformations is reproduced via linearization of the governing equations. As an application example, we derive an exact solution for the finite-deformation problem of a flexoelectric bar. Our exact solution demonstrates remarkable distinctions between nonlinear flexoelectricity and linear flexoelectricity. To underpin the theoretical framework with numerical examples, we establish a mixed finite element formulation for nonlinear flexoelectricity and investigate the finite-deformation problem of flexoelectric solids with a circular cavity. We meticulously highlight the impact of nonlinear effects on electric potential, electric polarization magnitude, and circumferential stress concentration. Our results advance higher-order electroelasticity from both theoretical and computational perspectives, revealing the significance of nonlinearities, hence offering novel insights for the design of soft flexoelectric devices.</p>