ABSTRACTThe use of modular building systems (MBSs) in the construction sector is increasing. MBSs enhance structural performance of buildings, quality control, and construction speed than traditional methods at a lower cost. Additional benefits can be associated with resource efficiency at both the production and construction phases, which may increase MBSs' attractiveness and popularity in the short‐ and long‐term future. In the UK, the government is planning to solve Britain's housing crisis by constructing more than 100,000 modular homes in an effort to meet its target to provide a million new homes by 2020. At the same time, the construction sector is facing post‐Brexit skills shortages, while it is undergoing a technological revolution. One outcome of the latter has been the production of cold‐formed steel (CFS) hollow flange sections, which can be optimised using genetic algorithm and finite element analyses in order to improve the load‐carrying capacity of modular buildings. These optimised CFS beams, employed in MBSs, can light gauge the frame building constructions. This paper presents a review of MBSs and the application of CFS hollow flange steel sections in construction. It then summarises some of the key outputs of numerical studies on the structural behaviour of hollow flange beams to justify its applicability in MBS.