<p>The current study explores the influence of thermal radiation on the flow of Casson liquid via a vertical microchannel in the presence of a magnetic field. Furthermore, the investigation of entropy generation may indicate options for increasing heat transport inside the microchannel. Entropy addresses the particular arrangement of particles and the principles of entropy as they pertain to a specific combination of measurements for temperature, pressure, and volume inside a microchannel of the system. Applications of entropy generation in nuclear energy: despite the substantial energy output of nuclear reactions, the earth has a finite supply of materials essential for these processes. The modeled governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) with the aid of similarity variables. The obtained ODEs are solved numerically by employing Runge–Kutta–Fehlberg’s fourth-fifth order (RKF-45) scheme. The influence of relevant parameters on Bejan number, entropy generation, velocity, and temperature is discussed graphically. The obtained outcomes are compared with the earlier available results. The upsurge in radiation parameter (1, 1.5, 2, 2.5) values declines the velocity. Results reveal that the heat transport declines for higher radiation parameter (1, 1.5, 2, 2.5) and magnetic parameter (1, 3, 6, 9) values. Entropy generation decreases with the increase in the Brinkman number and magnetic parameter, the reverse trend is observed for the radiation parameter.</p>