The significance of the dynamics of mixture of polymethyl methacrylate and pyridine at 25 C containing 30.5 g of polymer per litre with density 0.98 g per litre has led to countable published facts with the intention to come up with insightful suggestions and recommendations for the expert in biofuel, bioengineering, biomedical, and mechanical engineering applications. However, nothing is known on the increasing bioconvection Rayleigh number, velocity ratio, Lorentz force, Prandtl number, bioconvection Peclet number, bioconvection Lewis number, and microorganisms concentration Biot number. The Spectral Local Linearization Method (SLLM) and MATLAB in-built package were adopted to solve the dimensionless form of the corresponding governing equation for the dynamics of radiative-reactive Walters-B fluid due to mixed convection when tiny particles experience haphazard motion, thermo-migration, and Lorentz force are significant and analyzed. It can be concluded that the Nusselt number proportional to the heat transfer rate can be declined by rising Lorentz force. The microorganism’s flux at the wall is a decreasing property of Prandtl number and bioconvection Peclet number. Increasement in the temperature distribution of the fluid flow is a property that could be enhanced through enhancement in the Lorentz force.