This study investigates the effects of magnetohydrodynamics (MHD) and bioconvection on Casson-Williamson nanofluid flow along a stretched sheet. Such a fluid dynamics analysis considers the impact of MHD, chemical reactions, and gyrotactic microorganisms. For velocity and magnetic field behavior exploration, the concept of buoyancy ratio has also been proposed in the study. The Casson and Williamson rheological models characterize the fluid properties to understand the effects of these parameters by the motion of motile gyrotactic microorganisms. Similarity variable is used to reduce nonlinear partial differential equations including boundary conditions to strong coupled ordinary differential equations, which are easier to analyze. The solutions can be obtained by the use of `bvp4c', a popular numerical method for nonlinear boundary value problems, which enables sensitivity about fluid dynamics of different physical parameters on profiles of ????′(????),????(????),????(????), ????(????), ????′′(????) and ????′(????). Numerous physical characteristics, such as the buoyancy ratio, thermophoresis variable, Brownian motion variable, bioconvection number, Eckert number, and thermal radiation, determine the behavior of non-Newtonian fluids. The result shows that the skin friction decreases by increasing the value of the magnetic field the Nusselt number decreases by raising the value of heat generation parameters and the Sherwood number increases by increasing the value of Lewis number. The study aims to notice the impact of buoyancy ratio and Rayleigh number on fluid behavior. The velocity profile declines by increasing the value of and and the temperature profile increases for thermophoresis and Brownian motion parameter value rise.