Radiation therapy serves as a fundamental treatment for primary and metastatic brain tumors, whether used alone or combined with surgery and chemotherapy. Despite its oncological efficacy, this treatment paradigm frequently induces radiation-induced brain injury (RBI), a progressive neuropathological condition characterized by structural and functional damage to healthy cerebral parenchyma. Patients with RBI frequently develop affective disorders, particularly major depressive disorder and generalized anxiety disorder, which profoundly impair psychosocial functioning and quality of life. The pathophysiology involves complex mechanisms such as neuroinflammation, oxidative stress, blood-brain barrier disruption, and white matter damage. Current management strategies include antidepressants, corticosteroids, and neuroprotective agents, while emerging therapies targeting neuroinflammation and neural repair show promise. This review comprehensively examines the pathogenesis of RBI-related affective disorders and evaluates both conventional and novel treatment approaches. By synthesizing current evidence, we aim to provide insights for developing more effective interventions to improve patient outcomes and quality of life.