Molecular self-assembly is ubiquitous in living systems, leading to the formation of innumerable biological complexes spatiotemporally regulated. Inspiring by nature, the novel methodologies, such as enzyme-catalyzed self-assembly and interfacial self-assembly, has been developed for the spatiotemporal control of self-assembly. It also enables molecular self-assembly to be regulated in cellular milieu, leading to the formation of assemblies at the specific position of living cells. The nanometric shell is able to be formed on the cell surface via the interfacial self-assembly of tannic acid and ferric ion, allowing to the protection of the cells against harmful stresses. The PRSS1-catalyzed self-assembly of peptide derivatives facilitates the selectively targeting of endoplasmic reticulum(ER) in OVSAHO cancer cell, promising the application in cancer therapy. These simple strategies for molecular self-assembly in cellular milieu will advance chemical manipulability of cell viability.