We propose a transient recombination‐enhanced defect‐generation model to analyze the degradation of optical output powers of blue‐green II–VI light‐emitting diodes (LEDs). We find an analytical solution and discover a set of universal curves for the time dependence of optical output power, which agree very well with the experimental data for strained CdZnSe quantum‐well structures. Our model shows that the optical power can be non‐exponential in character and its long‐time behavior has a 1/t dependence. This 1/t dependence is also related to the growth of the defect density, which should behave as a t1/2 dependence. The generation of new defects due to electron‐hole recombination at the defect sites is found to be the dominant degradation mechanism for II–VI LEDs.