Controlled architecture of bifunctional polymers on surfaces is highly challenged because of the stringent reaction conditions or tedious operations required for surface modification. Herein, a simple and effective method was developed to assemble zwitterionic and cationic binary polymer brushes onto polydopamine-anchored stainless steel (SS) surfaces. Zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was first graft polymerized from the functionalized SS surface via thiol-ene "click" reaction. Allcynyl-modified cationic poly(2-(methacryloyloxy) ethyl trimethylammonium chloride) (alkynyl-PMETA) was subsequently introduced via azide-alkyne "click" reaction. After the grafting of PMPC/PMETA binary polymer brushes, the resulting" functionalized SS surfaces can cooperatively reduce the adhesion of Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Pseudomonas sp., as well as the attachment of microalgae Amphora coffeaeformis. In addition, the binary polymer brushes coatings were ascertained to be stable and durable after 30-day exposure to filtered seawater. Thus, surface functionalization with zwitterionic and cationic binary polymer brushes offers an environmentally friendly alternative for biofouling inhibition in the marine and aquatic environments. In addition, surface modification via dual "click" reactions provides another alternation for developing surface coatings with multifunctionalities.