Electrochemical synthesis, known for its low waste, high selectivity, and mild reaction conditions, has recently attracted attention as a clean approach for small molecule conversions. Because of these advantages, electrochemical synthesis has been studied as a method for direct late-stage modification of complex compounds. The potentials make it a promising technique for chemical modification of proteins, which often contain numerous reactive functional groups and can be challenging to purify from a reaction mixture with excess labeling reagents.