The growth of the electric vehicle market has driven the advancement of technologies related to energy storage and lithium-ion cells, which stand out for their fast charge and discharge capabilities, high energy density, and long service life. This paper proposes a thermal control strategy for lithium-ion battery packs using the Active Disturbance Rejection Control (ADRC) method. The model is developed in Simcenter Amesim software, using cylindrical 21700 cells in a pack equipped with a water-cooling system, and was adapted for export in FMU format and integrated into MATLAB/Simulink, where the control algorithms were designed and simulated. From step input tests, a first-order transfer function was identified with a fitting of 97.67%, supporting the adoption of a first-order ADRC. The tests involved scenarios with changes in temperature reference and current disturbances typical of vehicle operation. Results indicate that ADRC performs satisfactorily in temperature tracking, even under actuator saturation, and particularly excels in disturbance rejection, outperforming the proportional-integral-derivative (PID) controller in speed and precision. Furthermore, ADRC proved robust to system degradation—an essential feature in the thermal management of batteries subject to aging. The proposed approach shows promise for real-world applications, offering thermal stability and extended system lifespan. For future work, experimental validation through Hardware-in-the-Loop (HiL) is suggested.