Artificial metalloenzymes have emerged as a promising approach to merge the attractive properties of homogeneous catalysis and biocatalysis. The activity and selectivity, including enantioselectivity, of natural metalloenzymes are due to the second coordination sphere interactions provided by the protein. Artificial metalloenzymes aim at harnessing second coordination sphere interactions to create transition metal complexes that display enzyme-like activities and selectivities. In this Review, the various approaches that can be followed for the design and optimization of an artificial metalloenzyme are discussed. An overview of the synthetic transformations that have been achieved using artificial metalloenzymes is provided, with a particular focus on recent developments. Finally, the role that the second coordination sphere plays in artificial metalloenzymes and their potential for synthetic applications are evaluated.