Immunotherapy medicines (immune checkpoint inhibitors, ICIs) that work directly on the immune system have shown vastly increased survival for people with cancer in phases 2 and 3 clinical studies during the past few years. Nevertheless, ICI treatment (irAEs) may trigger immune-related adverse effects. An underactive thyroid is among the most frequent endocrine irAE, affecting about 40% of individuals who received ICIs. Our review aims to collect and organize the most recent data on immunotherapy-induced thyroid dysfunction in cancer patients, including its prevalence, diagnostic criteria, and treatment options and to summarize those findings in a comprehensive review article. The incidence of irAEs varies depending on the type of cancer and the treatment regimen. Thyroid ultrasound, radioactive uptake scan, and PET CT scan can aid in diagnosing thyroid dysfunction. Thyroid dysfunction treatment necessitates collaboration between specialists in oncology, endocrinology, and primary care in a multidisciplinary team discussion. The prognosis of patients who suffered from thyroid dysfunction while on ICIs treatment is reasonably good. Suboptimal baseline thyroid function was linked with decreased overall survival (OS) among ICI-treated patients, but initiating replacement hormonal therapy after ICI initiation was associated with enhanced OS. More research work is required to identify these links and mechanisms of action.