Modular construction (MC) shifts labour-intensive site-based activities to an off-site controlled environment through prefabrication, and is deemed an innovative approach for industry transformation. To maximise the benefits of MC, there is a need to predict the demand volume and supply capacity to inform proactive and strategic supply chain planning and development. This study aims to provide a holistic exploration of the factors influencing the MC market, based on a literature review and a study of the case of modular integrated construction (MiC) in Hong Kong. A systematic framework was proposed with 15 demand-related factors and 10 supply-related factors to explain the complex influential mechanism from the political, economic, social, technological, environmental, and legal (PESTEL) perspectives, which contribute to the understanding of the dynamic evolution of the MiC market. The findings revealed that the influencing factors are manifold, with the political factors influencing the MiC demand the most and the economic factors determining the development pattern of the MiC supply. The presented study lays a foundation for the establishment of a practical MC demand-and-supply model for better market planning. Attention should be devoted to rationalising the quantification of qualitative factors in future research.