Ultrahigh-speed laser cladding (UHSLC) has high efficiency and offers excellent properties for the prepared coating. Meanwhile, eutectic high-entropy alloys (EHEA) are commonly used in surface modification engineering. In this study, 19Al-24Cr-19Ti-37Ni-1Y EHEA coatings with different aging times at 650 °C were characterized and tested for mechanical properties. Results showed that the eutectic organization in the coating was significantly coarsened with the increase in aging time, and the reduction of the phase interfaces weakened the interfacial strengthening effect. In addition, the precipitated phase underwent dissolution, which was 63.1% lower than that before aging, and the reduction in size and number made the Orowan strengthening effect weaker. With the increase in aging time, the hardness and wear resistance of the coating deteriorated. When the aging time was 2160   h, the room temperature hardness decreased by about 246HV 0.5, and the high-temperature hardness was only 298HV 0.5, which was less than half of that of the coating before aging; the coefficient of friction increased by 40.6%, and the volumetric wear rate deteriorated by more than 5 times. The deterioration in the performance of the EHEA coating after long aging treatment demonstrated the limitations of the UHSLC process in preparing EHEA coatings for high-temperature applications over a long period of time.