This paper aims to offer an overview of the features in the existing state of research on blockchains in the circular economy. A total of 79 articles published up to 31 May 2022 have been extracted from Scopus and Web of Science. The research design has enabled us to identify what characterises the present state of research on the use of blockchains in the circular economy. It has also allowed us to obtain a new categorisation scheme of the research that has identified five themes and the contributions in each theme and has allowed us to highlight several research gaps. The review findings indicate that the literature revolved around five research themes, namely, the relationship between blockchains and Industry 4.0, the potential of blockchains for circular economy practices, the role of blockchains in energy management, the role of blockchains in waste management and the impact of blockchains on sustainability. This review suggests several future research opportunities and provides practical implications for researchers and practitioners. To the authors' best knowledge, this study represents one of the first attempts to investigate the interplay between blockchain technology and the circular economy.