Workplace ergonomics plays a crucial role in maintaining productivity and preventing musculoskeletal disorders (MSDs), which remain among the most common occupational health issues in manufacturing environments. At PT. X, a large-scale automotive manufacturing company in Indonesia, clinic data indicated that prior to 2022, the monthly average of visits related to fatigue and posture related complaints reached 434 cases. Following the implementation of an AI-powered ergonomic evaluation system in 2023, this number decreased significantly to 91 cases per month. The system was developed to automate posture assessment using computer-vision techniques, integrating Open Pose for human-pose estimation and a proprietary classification algorithm derived from the internal TEBA (T-Ergonomic Burden Assessment) framework, which references RULA and REBA standards. A pilot study was carried out at a standing assembly workstation using fixed and movable webcams to capture operator movements in real time without interrupting production. The AI model classified postures into ergonomic risk categories and automatically generated summary reports after each observation. Implementation results demonstrated measurable improvements: average evaluation time per operator decreased from 30 to 6 min (a 60% productivity increase), and indirect ergonomic related costs were reduced by 83%. The notable decline in MSD-related clinic visits also reflected tangible improvements in workplace well-being. These findings confirm that integrating AI into ergonomic evaluation not only increases operational efficiency but also advances human-centered digital transformation aligned with Industry 4.0 principles.