The most recent Special Issue from The FEBS Journal, available to read here: https://febs.onlinelibrary.wiley.com/toc/17424658/2020/287/7, is composed of 10 extraordinary reviews that delve into the intricacies behind enzyme promiscuity and evolution, which is an area that is of increasing interest within the biological research community. In particular, the reviews in this Special Issue explore enzyme promiscuity and evolution in the context of cellular metabolism. The guest editor for this Special Issue, Dan Tawfik, presents a captivating review describing how evolution shapes enzyme selectivity. Other intriguing topics covered include the evolution of bioluminescence, as well as the evolution of new enzymes by gene duplication and divergence. It is our hope that you enjoy these fascinating and informative reviews and we wish to thank the authors for their compelling contributions to The FEBS Journal.