Malnutrition is a common problem in patients with head and neck cancer (HNC), including oropharyngeal cancer (OPC). It is caused by insufficient food intake due to dysphagia, odynophagia, and a lack of appetite caused by the tumor. It is also secondary to the oncological treatment of the basic disease, such as radiotherapy (RT) and chemoradiotherapy (CRT), as a consequence of mucositis with the dry mouth, loss of taste, and dysphagia. The severe dysphagia leads to a definitive total impossibility of eating through the mouth in 20–30% of patients. These patients usually require enteral nutritional support. Feeding tubes are a commonly used nutritional intervention during radiotherapy, most frequently percutaneous gastrostomy tube. Recently, a novel HPV-related type of OPC has been described. Patients with HPV-associated OPC are different from the HPV− ones. Typical HPV− OPC is associated with smoking and alcohol abuse. Patients with HPV+ OPC are younger and healthy (without comorbidities) at diagnosis compared to HPV− ones. Patients with OPC are at high nutritional risk, and therefore, they require nutritional support in order to improve the treatment results and quality of life. Some authors noted the high incidence of critical weight loss (CWL) in patients with HPV-related OPC. Other authors have observed the increased acute toxicities during oncological treatment in HPV+ OPC patients compared to HPV− ones. The aim of this paper is to review and discuss the indications for nutritional support and the kinds of nutrition, including immunonutrition (IN), in HNC, particularly OPC patients, undergoing RT/CRT, considering HPV status.