This review article discusses the use of noncanonical amino acids (ncAAs) in biocatalysis and enzymology. It highlights the advancements in genetic code reprogramming methods that allow the introduction of new functional components into proteins as ncAAs, expanding the chemical diversity of amino acids. The article covers various enabling technologies, including post-translational protein modifications, solid-phase peptide synthesis, selective pressure incorporation, and genetic code expansion. It also explores how ncAAs have been used to probe enzyme mechanisms, enhance enzyme function, and design new catalytic mechanisms. Specific examples are provided for each application, such as incorporating spectroscopic handles, trapping reactive intermediates, modulating noncovalent interactions, and tuning enzyme activity. The review concludes by discussing the potential of genetic code reprogramming as a powerful tool in enzyme engineering and design.This review article discusses the use of noncanonical amino acids (ncAAs) in biocatalysis and enzymology. It highlights the advancements in genetic code reprogramming methods that allow the introduction of new functional components into proteins as ncAAs, expanding the chemical diversity of amino acids. The article covers various enabling technologies, including post-translational protein modifications, solid-phase peptide synthesis, selective pressure incorporation, and genetic code expansion. It also explores how ncAAs have been used to probe enzyme mechanisms, enhance enzyme function, and design new catalytic mechanisms. Specific examples are provided for each application, such as incorporating spectroscopic handles, trapping reactive intermediates, modulating noncovalent interactions, and tuning enzyme activity. The review concludes by discussing the potential of genetic code reprogramming as a powerful tool in enzyme engineering and design.