Background: Regular participation in physical activity (PA) may help mitigate adverse side effects and symptoms associated with cancer treatments. It is recommended that cancer survivors engage in 150 minutes of moderate-to-vigorous intensity physical activity (MVPA) each week, but most do not follow these recommendations. Identifying theory-based factors associated with MVPA is important to understand how to promote PA engagement in this population. We examined whether Health Belief Model (HBM) constructs (i.e., perceived susceptibility of cancer, perceived severity of cancer, perceived benefits of PA for reducing cancer risk, perceived barriers to PA, PA barrier self-efficacy) were associated with self-reported MVPA behaviour in cancer survivors. Methods: 98 adult cancer survivors (Mage=48.9±15.2 years; 80.6% female) completed an online survey assessing sociodemographics, medical characteristics, MVPA behaviour, and HBM constructs. Data were analyzed using hierarchical linear regression analysis. Results: After adjusting for age, sex, body mass index, and time since cancer diagnosis, HBM constructs accounted for 31.5% of the variance in MVPA behaviour. Only perceived benefits of PA (B=7.96, SE=2.66, 95% confidence interval (CI): 2.75-13.18, p=.003) and PA barrier self-efficacy (B=0.44, SE=0.09, 95% CI: 0.26-0.63, p<.001) were significantly associated with MVPA behaviour. Discussion: Results suggest that perceived susceptibility and severity of cancer may not serve as cues to action for MVPA engagement in cancer survivors. Rather, they suggest that efforts aimed at highlighting the benefits of MVPA for the prevention of cancer recurrence and strengthening cancer survivors' self-efficacy to overcome PA barriers may be important targets for the promotion of MVPA engagement in this population.