Abstarct: Abstract Functionally graded porous materials, known for their superior mechanical properties and customizable porosity distributions, offer enhanced structural performance under complex loading conditions and have been widely utilized in advanced engineering applications such as aerospace, marine structures, and biomedical implants.This study develops an analytical approach to investigate the post-buckling behavior of functionally graded porous shells with double curvature, resting on an elastic foundation and subjected to mechanical, thermal, hygro-thermal and hygro-thermo-mechanical loadings. The shell's material properties are considered temperature-dependent, while the boundary conditions are assumed to be simply supported on all four edges. The elastic foundation is modeled using Winkler and Pasternak parameters, while the strain-displacement relationships are derived baxsed on von Kármán–Donnell nonlinear equations and a high-order shear deformation theory, with the nonlinear static analysis performed through the Galerkin method in combination with a stress function approach. The investigation addresses the effects of porosity, shell curvature, displacements, elastic foundation stiffness, and humidity on the post-buckling response under the specified loading scenarios. Furthermore, the influence of temperature gradients, porosity distributions, and different boundary conditions is examined for hygro-thermo-mechanical, thermal, and hygro-thermal loadings, with porosity distributions being analyzed in uniform, symmetric, and asymmetric configurations to account for various design requirements. It has been observed that shells with higher porosity exhibit reduced buckling load capacity, with defect-free shells demonstrating superior mechanical and thermal load-bearing performance compared to those with initial geometric imperfections, and elevated temperatures further diminishing their buckling resistance.