Characterizing the kinetics of biomolecular interactions is fundamental for understanding biological mechanisms, developing novel drugs, and optimizing processes in protein engineering. Although modern surface-based methods have advanced our understanding of protein-protein and protein-ligand kinetics, they rely on immobilized samples, preventing the study of interactions under native conditions and leading to an incomplete understanding. We propose a paradigm shift by introducing a method based on flow-induced dispersion analysis to study interaction kinetics while keeping biomolecules in solution, eliminating the need for surface immobilization and ensuring truly native binding conditions. The method examines reactions outside equilibrium by inducing a rapid concentration change in one of the binding partners (C-Jump) in a controlled microfluidic environment. Notably, it operates without buffer restrictions and requires minimal sample quantities. We demonstrate C-Jumps capability by accurately determining the association and dissociation rates of protein-protein and protein-small molecule interactions. Furthermore, we validate its robustness by measuring a protein-protein interaction in human serum and a protein-small molecule interaction in-solution, label-free. This underlines C-Jumps broad applicability for studying biomolecular interactions under true native conditions, offering a powerful tool for protein engineering and drug discovery, as well as enabling characterization of previously inaccessible interactions.