The paper presented here discloses a detailed analytical study as to how the Casson fluid flows with characteristic properties of heat and mass transfer in an unsteady convective magnetohydrodynamic environment under the influence of thermal diffusion and chemical reaction. With the said characteristics, the fluid flows past over an oscillating vertical plate. The applicable partial differential equations are solved analytically using the perturbation technique and numerically using Matlab software. With the help of velocity, temperature and concentration, skin friction, Nusselt number, and Sherwood number are obtained and represented in tabular form. One of the important findings of this analysis includes that intensification in the Newtonian heating effect causes a gradual downfall in the rate of heat transfer at the plate and the concentration of the fluid decreases under the impact of a chemical reaction. Their physicochemical features have been dealt with in detail. This fluid flow model has several industrial applications in the fields of chemicals, polymers, medical sciences, and so forth.