Intermediate care units (IMCUs) have become increasingly important in the care of critical and semi-critical patients, particularly during the COVID-19 pandemic. However, there is still no clear definition of their structural characteristics, specialties, types of patients, and the benefits they provide. The aim of this work is to describe the current state of implementation and operation of IMCUs in hospitals and patient care. To achieve this goal, a systematic review was conducted in the Web of Science, Scopus and CINAHL databases, along with a hand search. The research yielded 419 documents, of which 26 were included in this review after applying inclusion and exclusion criteria. The results were highly diverse and were categorized based on the following topics: material resources, human resources, continuity of care, and patient benefits. Despite the different objectives outlined in the studies, all of them demonstrate the numerous benefits provided by an IMCU, along with the increased relevance of this type of unit in recent years. Therefore, this systematic review highlights the benefits of IMCUs in the care of critical patients, as well as the role of health workers in these units.