Significance Pharmaceutical practice has transitioned away from small-molecule drugs to the use of biomolecules (peptides, proteins, and antibodies). Where formulation of small molecules focused primarily on solubility, biopharmaceuticals introduced an array of complications due to their more complex secondary and tertiary structures, contributing to concerns surrounding aggregation and denaturation over time in formulation. Here, we outline an approach using noncovalent supramolecular affinity to endow biopharmaceuticals with a polymer known to inhibit protein aggregation and improve solubility. This method stands in contrast to similar approaches to covalently graft the same polymer onto the protein, instead offering a broadly useful and modular formulation excipient that can be combined with authentic unmodified protein drugs to extend shelf life.