<p>This study analyses the simultaneous impact of energy activation, thermal radiation, and porous medium on advection–diffusion transport of heat and mass in multi-nano-Casson fluid. The thermal and species transport through fluids has numerous industrial applications. For efficient transport of heat and mass, thermal conductivity and mass diffusion coefficient are required to be high. Therefore, multi-nanoparticles are considered to be dispersed to enhance the transport mechanism. Three combinations of these nanoparticles are: Fe₃O₄ + Co + Ni (called tri-nanoparticles), Fe₃O₄ + Co (called di-nanoparticles) and Fe₃O₄ are considered. Activation energy and the magnetic field have significant effects on the heat transfer procedure. The governing PDEs are transformed into ODEs and solved numerically. The behavior of the skin friction coefficient, the Nusselt number, and the Sherwood numbers versus related parameters is studied. Joule heating causes a temperature rise and, therefore, the thermal efficiency of the working fluid is reduced. Moreover, Joule heating is responsible for increased thermal boundary layer thickness. A destructive chemical reaction is responsible for an increase in wall mass flux, whereas a generative chemical reaction is responsible for a decrease in wall mass flux. The thermal performance of the fluid with greater yield stress is smaller than that of the fluid with smaller yield stress. Thus, Newtonian fluid is less efficient in transporting heat than Casson fluid (fluid with yield). Thus, viscoplastic fluids are thermally efficient in comparison with Newtonian fluids.</p>