Sarcopenia is recognized as a crucial factor impacting the prognosis, treatment responses, and quality of life of HNC patients. This review discusses various mechanisms, including common etiological factors, such as aging, chronic inflammation, and metabolic dysregulation. Cancer-related factors, including tumor locations and treatment modalities, contribute to the development of sarcopenia. The clinical implications of sarcopenia in HNC patients extend beyond reduced muscle strength; it affects overall mobility, reduces quality of life, and increases the risk of falls and fractures. Sarcopenia serves as an independent predictor of postoperative complications, chemotherapy dose-limiting toxicity, and treatment outcomes, which affect therapy planning and perioperative management decisions. Methods to assess sarcopenia in HNC patients encompass various techniques. A sarcopenia assessment offers a potentially efficient and readily available tool for clinical practice. Interventions and management strategies for sarcopenia involve exercise interventions as a cornerstone; however, challenges arise due to patient-specific limitations during cancer treatment. A routine body composition analysis is proposed as a valuable addition to HNC patient management, with ongoing research required to refine preoperative exercise and nutrition programs for improved treatment outcomes and survival.