The chemically reactive unsteady 3D Sisko fluid flow over a bidirectional stretched surface in the presence of nonlinear thermal radiation and magnetic field is considered. The numerical scrutiny of the transformed nonlinear ODEs is performed with the help of a numerical technique known as bvp4c. The mechanism of heat and mass transfer by the applications of chemical reaction and radiation is presented using temperature and concentration graphs. A remarkable enhancing results are estimated in the presence of nonlinear thermal radiation parameter $R_{d}$ and temperature ratio parameter $\theta_{w}$ for the temperature field. Another significant decreasing outcomes are found while plotting the concentration profile with variation of homogeneous and heterogeneous parameters ($k_{1}, k_{2}$). Computational results of the local skin friction and local Nusselt number are tabulated under the influence of physical parameters which governs the flow. Decrease in skin friction with varying values of $\lambda$ is observed. On the other hand, the impact of $R_{d}$ and $\theta_{w}$ on the tabular values of local Nusselt number is found in increasing order. All the graphical results and tabular values are illustrated while testing both cases of power-law fluids including pseudoplastic (0 & lt; n & lt; 1) and dilatant (n & gt; 1) behaviours. A comparison of the bvp4c and shooting technique with RK-45 Fehlberg is presented which shows excellent agreement. Additionally, the present results are compared with the results in the existing literature and both are found to be in very good correlation.