As potent and selective therapeutic agents, peptides and proteins are an important class of drugs, but they typically have suboptimal pharmacokinetic profiles. One approach to solve this problem is their conjugation with "stealth" polymers. Conventional methods for conjugation of this class of polymers to peptides and proteins are typically carried out by reactions that have poor yield and provide limited control over the site of conjugation and the stoichiometry of the conjugate. To address these limitations, new chemical and biological approaches have been developed that provide new molecular tools in the bioconjugation toolbox to create stealth polymer conjugates of peptides and proteins with exquisite control over their properties. This review article highlights these recent advances in the synthesis of therapeutic peptide- and protein-stealth polymer conjugates.