Abstract <p>This paper investigates the nonlinear post-buckling behavior of functionally graded porous double-curved nanoshells (FGP-DC-NS), which rest on elastic foundations and are subjected to uniform lateral pressure in a thermal environment. The temperature-dependent properties of the nanoshell, are graded across its thickness by employing a modified rule of mixture and power-law function. The formulation of the double-curved nanoshell employs the nonlocal elasticity theory and classical shell theory (CST), incorporating von Kármán type kinematic nonlinearity. The nonlinear system of equilibrium equations for the double-curved nanoshell is derived using the principle of minimum total potential energy. The governing equations are reformulated in their non-dimensional form to address the case of functionally graded porous double-curved nanoshells with immovable edges. Closed-form solutions are obtained in this study by adopting the two-step perturbation technique. The numerical outcomes are centered on Si3N4/SUS304 FGP double-curved nanoshell. Numerical parametric analysis and three types of porosity distribution are carried out to examine the effects of the small-scale parameter, geometric parameters, material properties, and temperature rise, on the post-buckling behavior of the FGP-DC-NS. These results indicate that the post-buckling behavior of the FGP-DC-NS remains stable in the face of uniform lateral pressure and thermal environment.</p>