Considering the rise of antibiotic resistance, the development of new antibacterial agents with improved biocidal functions is urgently required. In this study, ionic 5,5-dimethylhydantoin (DMH) analogues containing either a quaternary ammonium moiety (2)–4) or a phosphonate functional group (5),–6), were designed and synthesized to investigate the possible enhancing effect of quaternary ammonium moieties on the antibacterial performance of N -chloramines. These ionic DMH analogues were converted to their N- chloramine counterparts either in free form or after being covalently immobilized on a polymer surface via the “click” chemistry method. In the subsequent antimicrobial assessment against multi-drug-resistant Escherichia coli (MDRE. coli ) and methicillin-resistant Staphylococcus aureus (MRSA), chlorinated 2 and 3, the cyclic N -chloramines with a structural cation, exhibited distinctly enhanced biocidal functions in solution and after immobilization on surfaces.