The self-assembly of supramolecular copolymers facilitates the preparation of multifunctional materials, with tunable mechanical, electronic, or bioactive properties. Compared to covalent copolymerization protocols, controlling the molecular weight, stability, and monomer sequence of a multicomponent supramolecular copolymer remains limited. Here, we report a light scattering investigation of the charge regulated supramolecular copolymerization in neutral buffer of physiological ionic strength, supported with electron microscopy and circular dichroism spectroscopy experiments. Dendritic anionic and cationic peptide comonomers self-assemble into AB-type heterocopolymers with a nanorod-like morphology, a thickness of 11 nm, and a mean length of up to 70 nm. The fidelity in the copolymerization is remarkably high, and excess of either monomer of up to 50 mol % in the feed ratio does not lead to chain stoppering. The narrow length distribution of the copolymers (D < 1.3) and high colloidal stability in physiological buffer support their applications as biomedical carrier materials.