The Industrialised Building System (IBS), is a modern building technique that combines off-site production with prefabricated components which has gained popularity because it is deemed to possess superior technical characteristics. Although IBS offers several advantages, including increased cost-effectiveness, sustainability, and efficiency, worker productivity in IBS projects in Malaysia is still below ideal. Therefore, the objective of this study is to identify factors affecting labour productivity and to recommend ways to increase labour productivity in IBS projects. The methodology involved gathering quantitative data via questionnaires of 234 professionals working on IBS projects in the Klang Valley, Malaysia. However, only 90 meet the requirements to give accurate answers since they have the required IBS handling projects experience. The key findings show that several factors significantly influence productivity, including worker efficiency, clear communication, use of technology, and workers well-being. Enhancing employee training, implementing modern technology, encouraging collaboration, and ensuring that project planning is executed are some recommendations to increase labour productivity in IBS projects. By addressing these challenges, the construction industry can fully utilise IBS and create innovation, sustainability, and economic growth. The research contributes to the larger discussion on increasing worker productivity in the construction sector and gives stakeholders helpful recommendations on making IBS projects more successful.