Aim The use of immune checkpoint inhibitor (ICI) therapy for head and neck cancer (HNC) management is rapidly evolving. While established supportive care models exist for traditional HNC treatments, the needs of patients receiving ICIs remain ill-defined. This study conducted a retrospective audit of patients who received ICI treatment for HNC to understand the nature of supportive care needs. Methodology A retrospective audit was conducted for all patients who received ICI treatment for mucosal or cutaneous HNC at a Brisbane tertiary hospital between January 2022-December 2023. Engagement with allied health (AH) services was reviewed from the start of ICI therapy to 6 months post-treatment. Results  Ninety-nine records were analysed over a mean audit period of 17 months (range 2–43). Of these, 20 patients had recurrent or metastatic mucosal disease, 37 had resectable cutaneous disease, and 42 had cutaneous disease not amenable to surgery due to tumour or patient factors. Mean age was 71.7 years. Frailty screening was completed in only 46% of patients aged >70 years, with 93% identified as vulnerable or frail. Engagement with AH services varied. Although 34% of patients experienced grade ≥2 immune-related adverse events (iRAEs), only 2% received AH management for iRAEs. Broader AH use was also reviewed. Thirty-six percent accessed AH for cancer- or treatment-related issues and 39% for noncancer comorbidities; 36% had no AH engagement. AH services were accessed by 90% of mucosal HNC patients. Younger cutaneous HNC patients receiving definitive treatment had minimal AH use, whereas AH uptake was higher among older patients with palliative or unclear intent and greater frailty. Conclusion Patients receiving ICI therapy for HNC represent a heterogeneous group, yet distinct patterns of supportive care need exist. Consistent frailty screening and systematic monitoring of iRAE impacts are needed to support timely identification and intervention for patients at risk.