The conjugation of macromolecules to proteins can offer a variety of benefits from enhanced in vivo stability of protein-polymer conjugates to targeted delivery of protein-antibody conjugates. Transition-metal mediated bioconjugation with boronic acids has been shown to effectively modify natural proteins site-selectively under mild conditions with accessible reagents, though has been limited to small molecule conjugation. This thesis is on the development of boronic acid based bioconjugation methods for protein-macromolecule bioconjugation. The first two chapters review developments in protein-polymer and boronic acid bioconjugation chemistry. The first chapter details protein-polymer conjugation techniques with a focus on direct conjugation of functionalized polymers onto natural amino acids of proteins. The second chapter discusses protein bioconjugation strategies utilizing boronic acids as the warhead. The development of protein-macromolecule bioconjugates with boronic acid-functionalized macromolecules is covered in chapters 3-5. Polymer-protein conjugates are efficiently prepared via Ni(II) mediated cysteine arylation with ortho-nitroarylboronic acid functionalized polymers in chapter 3. In chapter 4, hetero-boronic acids containing an ortho-nitroarylboronic acid and a alkenylboronic acid moiety are used to conjugate cysteine containing proteins to dipeptide pyroglutamate-histidine tagged peptides and proteins. Finally, in chapter 5, phenylboronic acid-tagged proteins are reversibly conjugated to salicylhydroxamic acid-functionalized molecules including a polymer and dendrimer.