Many engineers and scientists are working on various studies such as cosmetics, medicines, chemicals, oil, gas, food and many others due to the numerous applications of non-Newtonian fluids in technological development and improvement. It is difficult to deal with non-Newtonian fluids compared to Newtonian fluids. Due to the vast applications, a numerical investigation of mixed and convective Casson liquid flow through a duct within a permeable medium under the Lorentz force effect is carried out. The problem is modelled mathematically by employing the mass, momentum, heat energy and conservation laws. The partial differential equations (PDEs) are changed into nonlinear ordinary differential equations (ODEs). These ODEs are numerically computed using the shooting technique and then validated through the Runge–Kutta–Fehlberg method. The influence due to Reynolds,Prandtl and Schmidt numbers and Casson, magnetic, porosity, thermal buoyancy and reaction rate parameters are illustrated graphically and in tabular representation to make the analysis more interesting. This study revealed that the transfer rates of heat energy and mass at the lower wall enhanced with the augmenting values of the thermal buoyancy parameter. There is a linear relationship between the velocity of the Casson parameter and Reynolds numbers. Moreover, velocity enhances with the higher magnetic and porosity parameters and diminishes with higher values of thermal buoyancy, Reynolds number and porosity parameters.