<p>Auxetic structures, distinguished by a negative Poisson’s ratio (NPR), exhibit homogeneous stress distribution during external force, rendering them optimal for augmenting the output response of energy harvesting systems. The innovative bioinspired butterfly-shaped auxetic structure represents a significant advancement over the conventional re-entrant auxetic design with NPR. It effectively integrates bionic principles to attain an enhanced NPR and improved mechanical performance. The primary goal of this study is to examine the influence of butterfly-shaped auxetic structures on bimorph cantilever energy harvesting systems. Two configurations are proposed: a full-sized auxetic design (BAEH1) and a patch auxetic design (BAEH2), both incorporating a tip mass and subjected to transverse loading. In this paper, we presume a parallel arrangement between the piezoelectric layers. The coupled electromechanical behavior of the BAEHs is modeled using Timoshenko beam theory, and an analytical method is developed to calculate their output responses. Three-dimensional finite element (FE) models are developed in COMSOL software to verify the analytical results, with convergence and comparative analyses used to verify precision and consistency. A parametric and stress analysis examines the impact of design parameters on power generation. FEM simulations reveal that the auxetic structure increases the total stress in the piezoelectric layer, contributing to a significant region exhibiting an NPR. Under identical conditions, the proposed BAEHs produce 50% to 70% more power than conventional designs. The findings presented highlight how bioinspired auxetic structures might improve piezoelectric energy harvesting for a range of industrial uses.</p>