<p>Health anxiety (HA) is a growing concern among medical students due to their continuous exposure to illness-related content, academic stress, and self-monitoring tendencies. While some studies suggest an association between HA and health-related behaviors, findings remain inconclusive, especially particularly among Chinese medical students. This study aimed to examine the relationship between HA and health-related behaviors. This cross-sectional study was conducted among 2,283 Chinese medical students. Participants completed standardized self-report measures assessing demographic characteristics, HA (via the Chinese Short Health Anxiety Inventory, CSHAI), body mass index (BMI), smoking status, dietary patterns, and physical activity levels (via the International Physical Activity Questionnaire–Short Form, IPAQ-SF). Group differences were examined using independent-samples <i>t</i>-tests and chi-square tests. Multiple linear regression was performed to identify factors associated with HA. Approximately one-third of the students reported clinically HA. Among participants, 46.3% were classified as physically inactive and 40.3% were overweight or obese. Additionally, 9.55% were current smokers, and 36.4% reported an unhealthy diet pattern. No significant differences were observed between students with and without HA in terms of BMI, smoking status, or dietary habits (<i>p</i> &gt; 0.05). However, weekly physical activity level was significantly lower among students with HA compared to those without HA (<i>p</i> &lt; 0.001). In regression analysis, physical activity was negatively associated with HA (<i>p</i> &lt; 0.001), indicating that higher levels of physical activity were related to lower HA scores (β= − 0.343). Lower physical activity was associated with higher HA, suggesting that promoting physical activity may be a relevant in efforts to reduce HA among medical students.</p>