The present investigation focuses on the numerical analysis of Casson fluid flow over an inclined nonlinear surface through a Darcy-Forchheimer permeable medium. This study takes into account various influential factors, including viscous dissipation, magnetohydrodynamics (MHD), radiation, chemical reaction, and Joule heating effects. The governing partial differential equations (PDEs) governing the problem are transformed into nonlinear ordinary differential equations (ODEs) using appropriate similarity transformations. The ODEs are subsequently solved utilizing the Keller Box method. The impact of the involved parameters is assessed by constructing profiles for velocity, temperature, and concentration. The velocity profile demonstrates a decrease with increasing values of the Casson parameter and the magnetic parameter, while it increases with higher permeability parameter values. Temperature exhibits an increase with progressive radiation parameter, Dufour parameter values, and the concentration profile experiences a decrease with higher values of the chemical reaction parameter.