Background/Objectives: Radiotherapy (RT) for head and neck cancer (HNC) is associated with oral and functional toxicity, but integrated data combining dental status, nutritional indicators and patient-reported outcomes remain limited. This study evaluated oral, dental, functional, nutritional and quality-of-life outcomes after RT. Methods: This exploratory observational study combined a retrospective record review with a prospective cross-sectional assessment of patient-reported outcomes and included 20 adults treated with RT for HNC in a regional Slovenian clinical setting. Clinical, oncological, dental and nutritional variables were extracted from records, while patient-reported outcomes were assessed once at post-treatment follow-up using the EORTC QLQ-C30, EORTC QLQ-HN43 and a focused oral-health questionnaire. Results: The median time from RT completion to questionnaire assessment was 3.0 months. Dysphagia, xerostomia and taste disturbances after treatment were recorded in 85.0%, 80.0% and 75.0% of patients, respectively. Trismus was present in 40.0%, and weight loss >10% in 55.0%. QLQ-HN43 domains with the highest burden included fear of progression, dry mouth/sticky saliva, problems opening the mouth, social eating, weight loss and teeth problems. Swallowing was strongly associated with social eating (rho = 0.798, p < 0.001), and mouth opening was inversely associated with patient-reported problems opening the mouth (rho = −0.610, p = 0.004). Conclusions: In this small exploratory cohort, substantial early post-treatment oral-functional morbidity was observed. The findings suggest the potential value of integrated survivorship follow-up incorporating dental, nutritional, functional, and patient-reported outcome monitoring.