Optimal ergonomic implementation is essential for creating a comfortable, safe, and productive work environment. This study aimed to analyze the work posture of Health, Safety, and Environment (HSE) workers at PT Cisadane Raya Chemicals using the Rapid Office Strain Assessment (ROSA) method. The ROSA method was chosen because of its ability to identify ergonomic risks based on worker interactions with office equipment, such as chairs, monitors, keyboards, mice, and telephones. The assessment was carried out on two respondents who showed ROSA scores of 6 each, which were included in the high-risk category. Based on the results of the analysis, a workplace redesign was performed using anthropometric data from the Indonesian community and ergonomic modeling software. The redesign included adjusting the dimensions of chairs and tables and adding supporting facilities such as document holders and lockers. In addition, recommendations were provided for changes in work habits and ergonomic training to increase worker awareness of the importance of good work posture. This study shows that ROSA-based ergonomic analysis and implementation of workplace redesign can significantly reduce musculoskeletal risks and increase work comfort and efficiency of workers.