Nature employs a limited number of genetically encoded, metal coordinating residues to create metalloenzymes with diverse structures and functions. Engineered components of the cellular translation machinery can now be exploited to genetically encode non-canonical ligands with user-defined electronic and structural properties. This ability to efficiently install ‘chemically programmed’ ligands into proteins can provide powerful chemical probes of metalloenzyme mechanisms and presents excellent opportunities to create metalloprotein catalysts with augmented properties and novel activities. In this concept article, we provide an overview of several seminal studies describing the creation of ‘chemically programmed’ metalloenzymes with interesting catalytic properties, and reveal how characterization of these systems has advanced our understanding of Nature’s bioinorganic mechanisms. We also highlight how powerful laboratory evolution protocols can be readily adapted to allow optimization of metalloenzymes with non-canonical ligands. This approach combines beneficial features of small molecule and protein catalysis by allowing the installation of a greater variety of local metal coordination environments into ‘evolvable’ protein scaffolds, and holds great promise for the future creation of powerful metalloprotein catalysts for a host of synthetically valuable transformations.