<p>The study aims to improve heat transfer in a heated mini-channel operating in the laminar regime by utilizing an external magnetic field together with a magnetic nanofluid containing CuO particles distributed in water to cool the batteries of electric vehicles (EV). The study was conducted for Reynold number ranging from 120 to 2000. In addition, the magnetic field intensity was adjusted to identify the optimal value that should be implemented. The magnetic field intensities were varied from 1000 to 2000 Gauss (G). Furthermore, the concentration of the CuO nanoparticles was also modified, ranging from 0 to 2% by volume fraction. The computational investigation, which involved varying parameters, revealed that the application of the magnetic field resulted in a maximum heat transfer enhancement of 127.96% when compared to that without the presence of a magnet for nanofluid as the working component. Moreover, the implementation of a magnetic field was observed to reduce pressure drop by 2–7%. However, a backflow was also observed in the channel flow following the application of the magnetic field. The formation of swirls in the flow, caused by the presence of magnets, contributed to the heat transfer augmentation. The thermal enhancement factor for all cases exceeded unity, providing evidence that the utilization of a magnetic field led to an improvement in heat transfer. The fundamental purpose of this study is to ensure that the EV batteries can operate at the utmost optimal temperature, thereby maximizing their overall performance of the system.</p>