In the medical industry, minimising biofouling is of utmost importance as it helps to reduce bacterial adhesion and prevent cross-infection. In this study, cyclized/knotted poly-divinyl-benzene (PDVB), a polymer with distinctive structural features, is proposed for the first time to be utilised in the preparation of antibacterial coatings. Firstly, cyclized/knotted PDVB is synthesised via deactivation-enhanced atom transfer radical polymerisation (DE-ATRP). The obtained PDVB coatings display remarkable antibacterial activity on both glass and titanium alloy substrates owing to their unique cyclised/knotted structure, effectively inhibiting the proliferation of common pathogenic bacteria. These research findings suggest that cyclised/knotted PDVB coatings possess outstanding physicochemical properties and demonstrate powerful antibacterial performance.