Abstract Tuberculosis (TB) remains a leading global cause of mortality, with prisons creating high-risk conditions for transmission due to overcrowding and limited access to healthcare. This cross-sectional study assessed the knowledge, attitudes, and TB screening practices of 345 Prison Health Volunteers (PHVs) across three correctional facilities in Chiang Mai, Thailand. Data were collected through questionnaires measuring socio-demographic characteristics, TB knowledge, attitudes, and screening practices from September to December 2023, and were analyzed using descriptive statistics and correlation tests. PHVs demonstrated high levels of TB knowledge (mean = 8.71 ? 1.42/10), positive attitudes (mean = 4.25 ? 0.48/5), and effective screening practices (mean = 4.02 ? 0.56/5). Statistical analysis revealed a significant but modest positive correlation between attitudes and screening practices (rsp = 0.180, P = 0.001). These findings suggest that attitudinal factors are more influential than knowledge alone in determining effective TB screening behaviors. This study demonstrated that Prison Health Volunteers (PHVs) exhibiting more positive attitudes toward TB screening engaged in more effective screening practices, irrespective of their knowledge levels or demographic characteristics. The findings suggest that attitudinal factors serve as a critical determinant of screening behavior, exerting a greater influence than knowledge.