AbstractThe pyrrolysine tRNA synthetase‐tRNA pair is probably one of the most promiscuous tRNA–synthetase pairs found in nature, capable of genetically encoding a plethora of noncanonical amino acids through stop codon reassignment. Proteins containing reactive handles, post‐translational modification mimics or both can be produced in practical quantities, allowing inter alia the probing of biological pathways, generating antibody–drug conjugates and enhancing protein function. This Minireview summarises the development of pyrrolysine amber stop‐codon suppression, presents some of the considerations required to utilise this technique to its greatest potential, and showcases the creative ways in which this technique has led to a better understanding of biological systems.