This paper presents the hygro-thermo-mechanical analysis of sandwich plates using an Equivalent Single Layer (ESL) approach under Carrera's Unified Formulation (CUF) with the introduction of five different non-polynomial shear strain shape functions (SSSFs). The laminated plates are subjected to hygro-thermo-mechanical loads with constant, linear and calculated profiles by the solution of Fick moisture diffusion law equation and Fourier heat conduction equation, each one individually, and in a coupled manner. Bending benchmark results are presented. The plate highly coupled governing equations are obtained by using Principal of the Virtual Displacement (PVD) and they are solved via Navier solution method. Finally, benchmark results are presented.