Casson–Williamson (CW) nanofluid flows and mass transfer characteristics are explored in this study. Furthermore, the velocity slip condition and viscous dissipation affect or are taken to examine the changes in mass and heat transfer caused by a stretching surface integrated into permeable media with heat conversion beneath the effect of a magnetic field and consistent thermal radiation. All the physicochemical characteristics of the non-linear fluids are regarded massive. Whether or not the concentration of nanofluids remains stable is investigated. When particles of a nanofluid are in motion, chemical reactions can occur, and this motion can be used to study the concentration of the nanofluid. One must first examine a set of non-linear partial differential equations with boundary conditions as a base equation to obtain the necessary BVP mathematical model. The approximate solution for differential equations was found using the finite difference method, which also considered the necessary boundary conditions. The numerical analysis results are then represented visually to demonstrate how different governing parameters affect velocity, temperature, and concentration. Although the heat transmission exhibits a reverse manner, the non-Newtonian nanofluid moves more quickly in the non-appearance of a magnetic domain than it does in one. Additionally, as the porosity parameter increased, the heat transmission rate decreased, whereas the skin friction coefficient increased. The novel parts of this study come from the simulation findings of a non-Newtonian CW nanofluid model in porous media subjected to a magnetic field, heat radiation, and slip velocity phenomena.