Dysphagia, a serious symptom of oral cancer, is also the most common. Further, patients who are more uncertain regarding their illness tend to catastrophize, which may affect their rehabilitation and long-term survival rate. Considering this relationship, this study aimed to investigate the occurrence of dysphagia in Chinese patients with oral cancer and explore the correlation between catastrophic cognition, illness uncertainty, and dysphagia. Applying a cross-sectional design, convenience sampling was used to recruit 180 patients with oral cancer. Advanced statistical methods were employed to analyze the mediating effects of catastrophic cognition on illness uncertainty and dysphagia. Chinese patients with oral cancer had a mean dysphagia score of 52.88 ± 10.95. Catastrophic cognition and illness uncertainty in patients with oral cancer were significantly positively correlated (r = 0.447, P < 0.001). There was a significant negative correlation between dysphagia score and catastrophic cognition (r = -0.385, P < 0.001), and between dysphagia and illness uncertainty (r = -0.522, P < 0.001). Bootstrapping results indicated that the mediating effect of catastrophic cognition between illness uncertainty and dysphagia was -0.07 (95% CI: [-0.15, -0.03]) and significant, and the mediation effect accounted for 15.6% of the total effect. Chinese patients with oral cancer have poor swallowing function. Results suggest that catastrophic cognition partially mediated the relationship between illness uncertainty and dysphagia in patients with oral cancer. Medical staff can improve patients' swallowing function by reducing the level of catastrophic cognition via decreasing the level of illness uncertainty.