The integration of robotics into flexible manufacturing systems (FMS) has been identified as a potential strategy for increasing modular construction flexibility. The purpose of this paper is to present a conceptual framework for investigating the relationship between FMS and robotics in modular construction. The framework proposes that by incorporating robotics into FMS, prefabricated building component manufacturing systems will gain flexibility. The two key variables of the framework are robotics (as the independent variable) and FMS (as the dependent variable). Moderator variables such as controlled environment and variability are also considered, as are mediator variables such as real-time adjustments, productivity, equipment utilization, set-up times, varying speeds, and reduced manpower. The purpose of this paper is to set the theoretical foundation for further studies on robotics integration into FMS in modular construction. The paper concludes with a discussion of the proposed implications of the framework for modular construction practitioners and researchers.