Chemical reaction and ohmic heating can significantly influence the flow behavior and heat transfer characteristics in industrial processes involving non-Newtonian fluids. These processes include polymer processing, food processing, and manufacturing processes where non-Newtonian fluids are commonly encountered. Therefore, the impacts of chemical reaction and ohmic heating on the unsteady flow of an incompressible magnetized non-Newtonian Casson liquid through a rectangular pipe with a variable pressure gradient is scrutinized in this article. The impacts of heat generation/absorption and viscous dissipation are also incorporated through the energy equation. The numerical simulations of partial differential equations (PDEs) are acquired utilizing the finite difference method with the incorporating relaxation (SOR) algorithm. The impacts of dissimilar imperative parameters on various flow fields are scrutinized through graphs. Outcomes indicate that liquid velocity decreases with enhancing values of the Casson parameter. Furthermore, the liquid temperature has an enhancing behavior with the impact of the heat source/sink parameter. Comparisons of numerical results with previously published results show an excellent agreement. This kind of research may find specific industrial and medical utilizations such as glass manufacturing, crude oil purification, lubrication, paper production, blood transport study in cardiovascular design, etc.