Nowadays, recent studies have demonstrated that plant-derived foods were characterized by their richness in bioactive phytochemicals and their consumption has a protective effect for human health. The effects of ionizing radiation on phytochemical properties of cooked L. (Mallow) were investigated. Irradiation increased significantly the total polyphenols and flavonoids content of cooked Mallow. Irradiation at 2 and 4 kGy doses resulted in a significant increase in the DPPH and ABTS radical-scavenging ability of cooked Mallow extracts. There was no significant change on carbohydrate, lipid, ash, and protein content. While the mineral composition of K and Na was affected slightly after irradiation, the amounts of Mg, P, Ca, Fe, Z, and Cu remain unaffected at 2 kGy and reduced slightly at 4 kGy. The antimicrobial activity was unaffected after irradiation. Postirradiation storage studies showed that the cooked irradiated Mallow was microbiologically safe even after 20 days of storage period. Sensory properties of cooked irradiated Mallow were unaffected by the treatment. This study supports that cooking process followed by gamma irradiation did not compromise the chemical composition and sensory characteristics of Mallow.