The aging population, particularly those aged 65 and above, is on the rise, with projections indicating a substantial increase in the elderly demographic. This demographic shift brings challenges in managing age-related diseases, including head and neck cancers (HNCs). Frailty, often characterized by physiological decline and vulnerability to stressors, is a crucial factor affecting treatment outcomes of elderly cancer patients. Accordingly, the significance of assessing frailty in elderly HNC patients before their treatment should be emphasized, but current frailty assessment tools may not fully capture the unique challenges faced by HNC patients. Specific indicators, including respiratory and swallowing functions, are proposed for a more tailored assessment. This comprehensive review explores the impact of frailty on various treatment modalities, including surgery, radiation, and chemotherapy, highlighting the need for personalized interventions. Furthermore, it suggests avenues for future research to enhance frailty assessment tools and investigate interventions aimed at improving treatment outcomes in elderly HNC patients.