This research conducts a thorough numerical examination to scrutinize the flow attributes of convective fluid infused with nanoparticles over a permeable stretching sheet. The nanofluid dynamics adhere to the Casson model, a framework of non-Newtonian type of fluid. Understanding the complexities of heat transfer events in the boundary layer-which take into account heat energy nonlinear radiation, nonuniform thermal energy sources and sinks, dissipation from Joule and viscous effects is the main goal of the research. The thermophoretic diffusion and Brownian motion of nanoparticles are included in the transport equations. Furthermore, a robust external magnetic field is introduced at an angle to the fluid flow, prompting the governing partial differential equations (PDEs) to undergo non-dimensionalization for simplification purposes. The PDEs are subsequently, transformed to ordinary differential equations (ODEs) by means of implementing similarity transformations. The transformed ODEs undergo quasi-linearization and local linearization processes to render the mathematical model in a solvable linearized form, which is then tackled using a spectral-based collocation method implemented in MATLAB. The impact of important flow-controlling parameters, including thermophoresis, Brownian motion, magnetic field inclination angle, thermal radiation, Eckert number, heat source/sink (depend on temperature), and the magnetic force parameter, is examined in depth in this investigation. The aim of the research is to offer additional insights into the concentration of nanoparticles, thermal transfer characteristics, and flow patterns. The graphical presentation of the findings enhances the conceptualization of these underlying phenomena. The outcomes of this study contribute valuable insights into convective fluid flow with nanoparticles, holding significance for diverse applications in engineering and industrial processes.