The importance of the circular economy has greatly increased in the past few years, and consequently, the interest in the circular economy as a research field has also increased, which led to an exponential growth in the number of literature reviews on the subject with different purposes. In order to analyze the topics that have been studied and assess the quality of these secondary reviews, this study carried out a tertiary literature review on the subject. This study identified the literature reviews on the circular economy, the most frequently cited papers, and the main research topics in the field. We have also analyzed the types of research questions that have been proposed by secondary studies. Finally, we evaluated the extent to which secondary reviews have assessed the quality of primary studies. We found out that literature reviews on the circular economy are frequently related to the areas of supply chain and technology. We also concluded that there is a need for designing research questions that explore more complex relationships, since most questions are descriptive or process-related. Some research questions are proposed to guide future studies. We also observed that secondary studies have failed to appropriately assess the quality of primary studies.