Interactions between molecules form the foundation of chemical and biological processes. Traditional theories have long described solvent–solute interactions in terms of polarity, hydrogen bonding, and thermodynamic stability. However, extending these frameworks to more complex biological systems, such as protein–drug interactions, remains challenging. This article introduces and applies a new theory in chemistry that bridges molecular-scale solvent–solute interactions with macromolecular protein–drug recognition. The theory provides a unified framework to explain binding energetics, specificity, and dynamic stability. Applications are discussed in both simple solution chemistry and advanced pharmacological systems, highlighting its predictive power for drug discovery.