Musculoskeletal disorders (MSDs) represent the most significant work-related health in occupational workers. This study aimed at determining the ergonomic factors associated with MSDs and risk assessment among farmers in Thailand. A cross-sectional analytical study was conducted of 71 farmers. The risk matrix assessment was used to identify risk levels. The finding found that 43 (60.6%) farmers were male, and 28 (39.4%) farmers were female. The association analysis demonstrated that education level, cigarette smoking, and work experience were majorly associated with the past 12-month of any MSDs (p  <  0.05). Farmers reported the highest prevalence of MSDs in the lower back (35.2%), followed by knees (33.8%), and shoulders (25.8%). In any MSDs, farmers reported 50.7% in the past 12-month. In ergonomics risk assessment, a matrix combining the risk levels of MSDs over the past 12 months with the Rapid Entire Body Assessment (REBA) risk levels revealed that among farmers, 8.6% individuals had an acceptable risk, 53.3% had low risk, 16.9% had moderate risk, 14.1% had severe risk, and 7.1% had a very severe risk level. The study suggests implementing ergonomics training among high to very high-risk farmers to prevent MSDs.