Inspired by the metamorphosis of pore-forming toxins from soluble inactive monomers to cytolytic transmembrane assemblies, we developed self-assembly-directed membrane insertion of synthetic analogues for permeability alteration. An expanded π-conjugation-based molecular precursor with an extremely high rigidity and a long hydrophobic length that is comparable to the hydrophobic width of plasma membrane was synthesized for membrane-inserted self-assembly. Guided by the cancer biomarker expression in vitro, the soluble precursors transform into hydrophobic monomers forming assemblies inserted into the fluid phase of the membrane exclusively. Membrane insertion of rigid synthetic analogues destroys the selective permeability of the plasma membrane gradually. It eventually leads to cancer cell death, including drug resistant cancer cells.