The purposes of the study were (1) to assess the physical activity (PA) status, muscle strength (MS), and flexibility of survivors of head and neck cancer (HNC) and compare these findings with normative data from national labor fitness measures; (2) to examine the differences among PA subgroups, as categorized using Godin's scores; and (3) to examine the association between stretching exercises and cervical range of motion (CROM). A cross-sectional study with consecutive sampling was used to recruit HNC survivors from a medical center in Northern Taiwan who had completed either radiation therapy (RT) or multimodality treatments including RT within the current 5 years. The level of PA, daily function, fatigue, quality of life (QOL), MS (handgrip and hip flexor), BMI, and flexibility (CROM and fingertip-to-floor tests) of the participants were assessed. A total of 108 participants completed the assessments from 135 eligible patients (80% response rate). Although 60.2% reported engaging in PA, only 16.7% met WHO guidelines. Compared to subjects in the normative data, the survivors of HNC in this study had poorer handgrip strength, BMI, and CROM, but better forward flexion. The participants who were consistent with WHO PA guidelines reported less fatigue, better right hip flexor MS, and better QOL than those who did not engage in any PA. Lack of sufficient PA and generally poorer fitness were found in study subjects. Longitudinal research to explore changes in fitness and barriers to PA compliance is strongly suggested to better enhance HNC patients' PA and fitness.