This study investigates the magnetohydrodynamic (MHD) flow of a Casson fluid (a non-Newtonian liquid that flows only after a specific yield stress is met) through a superhydrophobic microchannel (a microscopic flow passage with extreme water-repelling walls that create high boundary slip). We analyze the combined physical effects of external magnetic fields, wall suction (drawing fluid inward), and injection (pushing fluid outward) on velocity and temperature profiles. The exact solution of the resultant governing equations is obtained. Particular attention is paid to how variations in the Casson parameter alter the yield stress, flow velocity profiles, and momentum boundary layer thickness. The results show that increasing the Casson parameter increases yield stress and internal resistance, leading to a pronounced reduction in fluid velocity across the microchannel. Furthermore, contrasting the suction and injection parameters reveals that suction stabilizes the boundary layer and suppresses velocity distribution, whereas injection enhances flow displacement near the superhydrophobic walls. The findings provide critical insights for optimizing microfluidic devices, drag-reduction systems, and smart biomedical transport mechanisms.