The increasing number of implant-related complications in orthopedic and dental surgery, especially peri-implant infections and poor osseointegration, requires the development of new materials that can simultaneously prevent microbial colonization and promote bone tissue attachment. One of the most effective approaches is focused on the functionalization of implant surfaces with antibacterial and biocompatible composites, with particular attention being paid to zinc oxide nanoparticles (ZnO NP) and calcium carbonate (CaCO₃). The formation of biofilms of microorganisms such as Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans on the implant surface significantly increases the risk of infection and subsequent implant failure. Due to concerns related to antimicrobial resistance and negative ecological effects of antibiotics, alternative antimicrobial solutions are being investigated, among which metal nanoparticles stand out. ZnO NPs show strong antimicrobial activity even at low concentrations while maintaining a high level of biocompatibility, especially when immobilized on the surface, which reduces their cytotoxicity and prevents the release of free particles into the body. In combination with calcium carbonate, a material known for its excellent biocompatibility and resorption, a composite is created that combines the antimicrobial properties of ZnO NPs with the osteoconductive properties of CaCO₃. More unstable, soluble modifications of CaCO₃ are chosen to allow faster resorption and stimulation of bone tissue regeneration. This functionalization is carried out by the layered deposition method, with the use of poly(allylamine hydrochloride) (PAH) as a layer for immobilizing nanoparticles, which further increases the stability of the system and controls the release of Zn²⁺ ions. Special attention is paid to the effect of the morphology and size of the nanoparticles on the antimicrobial efficacy, as well as the effect of the combined presence of CaCO₃ and ZnO NPs on cell attachment and bone regeneration. By using a non-standard composite, which has not been described in the literature so far, the research contributes to the development of advanced, multifunctional surface coatings for implants that can simultaneously prevent infections and promote osseointegration.