Immunotherapy with immune checkpoint inhibitors (ICIs) has transformed cancer treatment over the past decade, improving survival rates in numerous advanced cancers. Immune-related adverse events (irAEs) are common and can affect any organ system, with many of these toxicities being well-characterized with clear grading criteria and management approaches. There has been less emphasis on oral manifestations of irAEs. This review provides an overview of oral manifestations of irAEs, including mucosal and salivary gland toxicities, and proposes a grading system and management guidelines. irAEs are common treatment-related toxicities in patients treated with ICIs. Oral irAEs can range from asymptomatic white reticulations to life-threatening mucocutaneous reactions requiring aggressive management with corticosteroids and/or permanent discontinuation of ICIs. Oral healthcare providers should be prepared to identify and manage oral irAEs in collaboration with oncologists and other specialists.