Abstract Se―N heterocycles have emerged as a promising class of bioactive molecules due to their unique redox properties and structural versatility. Such compounds exhibit good antioxidant activity and effectively mimic the function of glutathione peroxidase (GPx), a key enzyme in oxidative stress regulation. Among them, ebselen (2‐phenyl‐1,2‐benzoisoselenazol‐3‐[2 H ] one), a five‐membered Se―N heterocyclic compound and its analogues have been extensively studied for their anti‐inflammatory and neuroprotective roles. Selenazoles, selenadiazoles, spiroselenuranes, and selenoxides further expand the organoselenium landscape, offering diverse mechanisms of biological action. Recent advances underscore their potential in therapeutic applications including cancer, neurodegeneration, and ferroptosis. This review highlights the structural evolution and biological relevance of Se―N heterocycles as emerging enzyme mimetics and drug candidates for future therapeutics in diseases under oxidative stress.