As a sustainable alternative to conventional cast-in-situ construction, modular construction (MC) offers several promising benefits concerning energy and waste reduction, shorter construction times, as well as increased quality. In addition, given its high degree of prefabrication, MC offers ideal conditions to solve the industry’s long-lasting productivity problem by implementing manufacturing concepts such as lean production and automation. However, in practice, the share of automation and robotics in the production process is still relatively low, which is why the potential of this construction method is currently far from being fully exploited. An overview of the particular barriers to implementing automation in the context of MC is still lacking. Therefore, a qualitative study was conducted including eight MC manufacturers from Germany, Austria, and Switzerland. Following a comprehensive literature review, expert interviews were conducted based on an academically proven framework. Thereby, seven barrier dimensions with 21 sub-categories could be identified. The findings of this study contribute to the understanding of current barriers to implementing automation in prefabrication and how they can be overcome most effectively. Additionally, recommendations for future research are proposed within a research agenda.