Immune checkpoint inhibitors (ICIs) have emerged as the newest pillar of cancer treatment, transforming outcomes in melanoma and showing benefit in a range of malignancies. Immune-mediated toxicities, stemming from increased activity within the T cell lineage, range from asymptomatic or mild complications to those that are fulminant and potentially fatal. Immune-mediated endocrinopathies include hypophysitis, thyroiditis, and insulin-dependent diabetes mellitus. These presentations, which may be vague and non-specific, can be life-threatening if not diagnosed and treated appropriately. This review considers the work-up and management of immune-mediated endocrinopathies and also considers the role of advanced practice practitioners in the management of immune-mediated toxicities. These state-of-the-art MASCC recommendations represent a comprehensive overview of the management and clinical work-up in those in whom the diagnosis should be considered.