As nanofiltration applications increase in diversity, there is a need for new fabrication methods to prepare chemically and thermally stable membranes with high retention performance. In this work, thio-bromo “click” chemistry was adapted for the fabrication of a robust covalently attached and ultrathin nanofiltration membrane. The selective layer was formed on a pre-functionalized porous ceramic surface via a novel, liquid-vapor interfacial polymerization method. Compared to the most common conventional interfacial polymerization procedure, no harmful solvents and a minimal amount of reagents were used. The properties of the membrane selective-layer and its free-standing equivalent were characterized by complementary physico-chemical analysis. The stability of the thin selective layer was established in water, ethanol, non-polar solvents and up to 150°C. The potential as a nanofiltration membrane was confirmed through solvent permeability tests (water, ethanol, hexane, toluene), PEG-in-water molecular weight cut-off measurements (≈700 g mol-1) and dye retention measurements.