In today's turbulent and complex times, the importance of the functional security and continuity of critical infrastructure (CI) is of particular importance. The Industry 4.0 (I4.0) toolset contains many technologies that support CI or are an integral part thereof. The purpose of this paper is to examine the relationship between CI and I4.0. The goal will be achieved by ( 1) conducting a systematic literature review using VOSviewer, (2) identifying leading research topics using Latent Dirichlet Allocation, (3) mapping the results obtained and identifying possibilities for further research. Web of Science, Scopus, and a set of specific keywords were used to select peer-reviewed papers presenting evidence of the considered connections. Selected clusters and topics were used to build a reference framework formed by relations between CI and I4.0. The results revealed that despite the popularity of both issues, studies examining the mutual relations between the same are lacking. The added value of the article is that it organizes the knowledge related to relations between I4.0 and CI, and indicates the research areas that require further scrutiny. It is the first comprehensive literature review focusing specifically on CI & I4.0.