The flow of fluid on a slandering stretchable sheet with variable thickness can have several engineering applications like design and optimization of, aerodynamic structures such as wings and airfoils, wind turbine blade design, efficient cooling systems for electronic devices, power plants and industrial processes. Keeping in view these important applications, this work explores Darcy-Forchheimer flow of magnetohydrodynamics (MHD) fluid across a slandering stretchable sheet with variable thickness in the presence of chemically reactive effects, and heat source. The flow is impacted by the combined influences of diffusive-thermo and thermo-diffusive phenomena. The fluid is set into motion along x-axis due to the stretching behavior of the sheet with y-axis as normal to it. Similarity transformations are employed to convert the modeled equations into nonlinear ordinary differential equations. It has observed as outcomes of this study that velocity distribution has augmented with expansion in viscosity factor and has declined with growth in permeability factor, inertia factor, and magnetic factor for both scenarios h1=0.0 and h1=0.5 where the impacts are more significant for the scenario h1=0.0. Thermal distribution has declined with augmentation in Prandtl number, permeability factor and Dufour number while has upsurge with escalation in thermal source factor for both scenarios h2=0.0 and h2=0.5. Concentration distribution has diminished with escalation in Schmidt number, chemical reactivity factor and has augmented with growth in Soret factor for both the scenarios h3=0.0 and h3=0.5 with more significant impacts in the scenario h3=0.0. Stream lines and contour lines for fluid flow have also sketched for the scenarios h1=0.0 and h1=0.5 as well as for M=0.0 and M=2.0. Validation of the proposed model and the methodology has ensured through comparison with fine agreement amongst current results and previously published work