AbstractAmino‐acid‐derived polyzwitterions and polybetaines (PBs) are two promising alternatives to non‐ionic polymers, for example, to increase tumor permeability. In this study, amino‐acid‐derived polyzwitterions are synthesized and a strategy to quarternize the amine in the side chain functional group is developed to combine the advantages of both types. The functional monomer is polymerized via reversible addition−fragmentation chain‐transfer polymerization for which a kinetic study is performed. Further, the impact of the permanent positive charge on amino‐acid‐derived polyzwitterions is studied based on two zwitterionic polymers obtained via post‐polymerization modification (PPM) of Poly(N‐acryloxysuccinimide) to allow good comparison between methylated and non‐methylated polymers. Circular dichroism shows that the stereocenter remains intact during PPM. pH titration and ζ‐potential measurements show that the methylated polymer has a negative ζ‐potential over the measured pH range and, therefore, the polymer remains zwitterionic over a broader pH range than its non‐methylated equivalent. Both polymers are well tolerated by mammalian cells up to concentrations of 1 mg mL−1. The study introduces a path to a new polymer class that combines the advantages of both PBs and amino‐acid‐derived polyzwitterions and highlights the impact a permanent charge has on the physiochemical properties.