Background <p>Despite well-documented benefits of physical activity (PA), adherence remains poor among head and neck cancer (HNC) patients. Emotional factors significantly influence PA behaviors in this population, yet their underlying interaction pathways are poorly understood. This study aimed to identify the influence of emotional factors on PA behavior in HNC patients using an extended theory of planned behavior (TPB).</p> Methods <p>Adhering to the STROBE checklist, we conducted a cross-sectional survey of 304 HNC patients. Path analysis and mediation analysis were employed to examine factors associated with PA behavior and their interrelationships.</p> Results <p>A high percentage of HNC patients (53.90%) were physically inactive. The path model demonstrated good fit: <i>χ</i>²/df = 1.644, NFI = 0.968, TLI = 0.969, CFI = 0.987, IFI = 0.987, RMSEA = 0.047. The model explained 44.50% of the variance in PA behaviors (<i>R</i>² = 0.445). Path analysis revealed that perceived behavioral control exerted the strongest influence on PA behavior, followed by intention, planning, perceived benefits and barriers, subjective norms, and attitudes.</p> Conclusion <p>Enhancing PA behaviors in HNC patients is imperative. The extended TPB model was useful for understanding PA intentions and behaviors among HNC patients in China. Interventions that incorporate the emotional factors identified in our study may provide an effective framework for supporting PA in this population.</p>