In this review, supramolecular catalysis refers to the integration of the catalytic process with molecular self-assembly driven by noncovalent interactions, and dynamic assemblies are the assemblies that form and dissipate reversibly. Cells extensively employ supramolecular catalysis and dynamic assemblies for controlling their complex functions. The dynamic generation of supramolecular assemblies of small molecules has made considerable progress in the last decade, though the disassembly processes remain underexplored. Here, we discuss the regulation of dynamic assemblies via self-assembly and disassembly processes for therapeutics and diagnostics. We first briefly introduce the self-assembly and disassembly processes in the context of cells, which provide the rationale for designing approaches to control the assemblies. Then, we describe recent advances in designing and regulating the self-assembly and disassembly of small molecules, especially for molecular imaging and anticancer therapeutics. Finally, we provide a perspective on future directions of the research on supramolecular catalysis and dynamic assemblies for medicine.