Small and medium-sized enterprises (SMEs) in the informal sector of Brazil, Russia, India, China, and South Africa (BRICS) play a critical role in boosting their nations’ economies. Informal entrepreneurship is an important source of economic development thanks to knowledge sharing and innovation extensively employed in this area. The BRICS countries are viewed as leaders in economic development, innovation, and knowledge transfer among developing countries; abundant research into the factors of their success has so far paid insufficient attention to the relationship between innovation and knowledge generated by the SMEs and their role in promoting the BRICS countries’ development. This paper attempts to narrow the gap by critically analysing the nexus between innovation and knowledge sharing among informal small and medium-sized enterprises in these countries. It offers a systematic review of academic sources obtained from EBSCOhost followed by a thematic analysis of secondary data and a discussion of its results, which, as we hope, will provide insights for development practitioners and researchers in BRICS countries.