A coupled CFD modelling for fire growth and evacuation modelling is conducted to evaluate the fire safety performance of a multistoried ready-made garments (RMG) building. The geometric and architectural features, occupant density, and other features of the factory are selected to represent those of a standard RMG building in Bangladesh. The smoke propagation and evacuation scenarios are selected to resemble some of the typical and often overlooked unsafe practices, such as open fire-doors, obstacle in the egress routes, and reduced exit numbers, observed in the RMG sector in Bangladesh. The effects of these practices are examined separately and in different combinations to obtain a comprehensive understanding of their effect on the occupant safety. It is observed that when there is no compartmentation in place near the stairway (resembling open fire doors), different areas of the building become untenable very quickly. If all the unsafe practices are considered at the same time (open fire door, obstructed egress route, and reduced number of exits), about 6% (334 out of a total of 5381) of the occupants fail to evacuate safely. This happens due to the reduction in visibility in smoke below the threshold that permits safe escape, considering the physiological and psychological effects of smoke on the way-finding ability and escape behavior of the occupants. The critical issue of the possible effects of these unsafe or non-standard practices in the garment factories on the safety of the workers has not been addressed in a systematic manner before. Therefore, the findings of this study can be useful in assessing the potential consequences of a fire-hazard due to the unsafe workplace practices even in the standard RMG buildings complying with relevant building codes.