Mushrooms are widely recognized as a superfood, being the only natural source of vitamin D 2 , which makes them a valuable dietary food. Their popularity is rapidly increasing in the current era of heightened health awareness. The present study examined the effect of UV-B and UV-C irradiation on the vitamin D 2 content, its stability, antioxidant capacity, color, and textural properties of Hypsizygus ulmarius. The results revealed that the initial vitamin D 2 concentration in untreated samples was 74.82 ± 0.09 μg/100 g dw. After 90 min of UV-B exposure, the vitamin D 2 content peaked at 6813.39 ± 0.04 μg/100 g dw. However, UV-C irradiation first led to a rise in vitamin D 2 levels, reaching their highest point (388.30 ± 0.01 μg/100 g dw) after 45 min, followed by their subsequent decline. Stability analysis showed that freeze-dried mushroom powder retained more vitamin D 2 than fresh sporocarps after 7 days of storage at 4 °C. The UV-B treatment significantly enhanced antioxidant properties, increasing TAA (35.84%), DPPH (17.77%), ABTS (11.57%), and FRAP (18.36%) values. The color and texture of the samples also changed postirradiation, with notable increases in hardness, springiness, cohesiveness, and color intensity, alongside a decrease in whiteness. The study concluded that UV-B irradiation effectively boosts the vitamin D 2 content and antioxidant capacity of H. ulmarius besides inducing some alterations in its optical and textural properties.