In the quest to stabilize thermal and biological systems, the present work contributes to the existing literature by utilizing an efficient numerical scheme on the investigation of thermal stability of a reactive Casson fluid flow in a squeezed electromagnetohydrodynamic actuator channel. The dimensional governing equations of the system are made unitless by introducing suitable dimensionless variables. The derived equations are solved by a numerical technique (spectral quasi-linearization method). The obtained results, in a nonspecial case, are compared with ones obtained by Runge-Kutta, and a significant agreement is established. We examine the effect of thermodynamic parameters on the thermal performance of the system. It is observed that some parameters, like the Frank-Kameneskii parameter (λ) and modified Hartmann number (Z), reduced thermal criticality value, resulting in a quick autoignition of the system. In contrast, the presence of the Casson parameter (β) and activation energy parameter (ε) increased thermal criticality value, leading to a delay in an autoignition during the combustion process.