Palm oil plantation workers are exposed to various occupational hazards—physical, chemical, and biological—that can lead to accidents and long-term health issues. This study evaluated the effectiveness of a tailored Occupational Health and Safety (OHS) training program in improving knowledge, attitudes, and practices among workers in a plantation in South Kalimantan, Indonesia. A total of 120 workers participated, divided equally into an intervention group (n = 60) and a control group (n = 60). The intervention involved 15 small-group sessions covering eight key OHS topics, delivered by trained cadres using printed and digital modules. A mixed-methods approach with an intervention and cross-sectional design was employed. Due to non-normal data distribution, the Wilcoxon signed-rank test was used to compare pre- and post-intervention scores. Statistically significant improvements were observed in the intervention group, with knowledge scores increasing from 55.47 to 71.60, attitudes from 61.87 to 68.13, and practices from 17.90 to 21.87 (p = 0.000). The proportion of workers with good knowledge rose from 5.8% to 83.8% (p < 0.001; OR = 84.6; 95% CI: 22.3–320.8), while poor attitudes dropped from 80% to 20% (p < 0.001; OR = 10.0; 95% CI: 4.2–23.8). Good safety practices also increased to 76.5% (p < 0.001; OR = 4.9; 95% CI: 2.0–12.3). In contrast, no significant improvements were observed in the control group (p > 0.05). These findings demonstrate the effectiveness of a context-specific OHS training program in enhancing safety-related behaviors among plantation workers. The study also emphasizes the importance of inclusive implementation strategies, particularly for contract workers and those with limited experience, to ensure equitable benefits. Future research should explore the long-term sustainability of these improvements and investigate organizational factors that may influence the success of OHS interventions. © 2026, Mahidol University - ASEAN Institute for Health Development. All rights reserved.