Volunteer firefighters often have lower cardiorespiratory fitness (CRF) and less access to health monitoring and fitness programs than career firefighters, yet few studies explore how individual and departmental factors influence their CRF. This study assessed associations between CRF and both firefighter-level (e.g., years of service, firefighting calls, and firefighter rank) and department-level (e.g., department characteristics and fitness infrastructure) factors among volunteer firefighters. Surveys were administered to United States volunteer firefighters and departments, capturing CRF and related characteristics. CRF was analyzed as both a continuous and categorical variable (≤8, >8–<10, 10–<12, ≥12 METs) using bivariate analyses and mixed effects linear and logistic regression. Among 569 incumbent volunteer firefighters from 41 departments, 79.9% did not meet the recommended 12 METs threshold. Only 56.8% of departments provided routine physical exams; 35.1% had a wellness coordinator or committee; and 40.5% offered fitness resources. More years of service were associated with lower CRF and reduced odds of meeting the 12 METs benchmark, while more frequent training and responding to more calls were associated with better CRF. These findings highlight individual and structural challenges for CRF in volunteer fire service, underscoring the need for targeted fitness support to protect firefighter health and community safety.