Industry 4.0 has reshaped the current manufacturing environment. The rising need for manufacturing systems to be agile, adaptable, resilient, and robust has expedited the adoption of smart manufacturing technologies. Industry 4.0 has the potential to be a key driver in improving the productivity of SMEs. Nevertheless, its implementation poses several challenges for these entities, including restricted access to financial and knowledge resources, along with the complexity of selecting relevant technologies. Thus, we conduct a systematic literature review in this paper in order to establish the level of existing research on how Industry 4.0 can be implemented in SMEs and how well it can address the challenges it poses. Additionally, this paper examines the various dimensions of Industry 4.0 maturity models, as well as how these maturity models can be used to guide SMEs in their transition to industry 4.0.