The objective of human factors engineering is to optimize socio-technical systems to enhance systems performance and human wellbeing throughout the systems lifecycle. The aviation industry is one of the sophisticated and influential industries popularized the principles of human factors engineering in response to aircraft incidents and accidents. Now, there has been a slow pace in the application of human factors in the lifecycle of socio-technical systems beyond the aviation industry. Lack of understanding of human factors benefits has been alluded to as one of the factors that hinder the application of human factors in other industries. A number of studies focus on the development and application of various human factors models, but there seems to be no study that adequately shortlists and presents benefits of applying human factors. The aim of this paper is to uncover, examine and classify the benefits of applying human factors engineering principles in sociotechnical systems, especially in the era of 4IR. A narrative literature review methodology was adopted to analyze and synthesize various conference and journal articles on the application of human factors. The study revealed and classified the benefits of human factors according to performance, wellbeing, safety, quality, cost, and other operational benefits. The main contribution of the study is making the benefits of applying HFE in various systems and processes visible to potential adopters and researchers involved in the application of HFE. Human factors such that they are visible to researchers and industry practitioners. Thus, it sets an agenda for future debate, discussion, and research.