To prevent the transmission of diseases caused by microorganisms, more and more focus was placed on the creation of antibacterial coatings. In this work, we reported a creative synthesis of antibacterial cationic 4-vinylpyridine polymer nanospheres (CvpPMs). The nanospheres of decreasing size were produced by the self-assembly of stiff polymer chains of styrene (St) and cationic 4-vinylpyridine (4vp) polymer. Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS) were employed to describe the CvpPMs' structural morphology and other characteristics. CvpPMs were N + -surfaced cationic nanospheres that had an average diameter of 250 nm. After evaluation against Staphylococcus aureus and Escherichia coli, the results showed a significant antibacterial rate of 98% after 72 h and, even more impressive, 95% after 120 h. The synergistic interaction of amphiphilic groups (ethylsulfobetaine methacrylate, SBMA) and quaternary ammonium pyridinium groups was responsible for the exceptional performance of CvpPMs. In addition, it mimicked the N + −π interactions of adhesion, which significantly enhanced its adhesion strength, and the coatings also achieved antibacterial rates of averaging over 95%. In conclusion, the type of antibacterial copolymer nanospheres hopes to offer an avenue for developing antibacterial coatings.