A nanoscale ternary layer-by-layer self-assembly (LbL) thin film was fabricated on brass via a simple dipping method. Dual driving force of intermolecular interactions and coordination realized the high homogeneous dispersion of Ce3+, thereby improving the controlled distribution and release of inhibitors. Compared to previous nanometer-thick conversion coatings, ternary LbL film exhibited excellent multifunctional corrosion protection. The maximum strengthening reached 496.8% in impendence, and corrosion inhibition efficiency remained 95.0% after a 10-day exposure in 3.5wt.% NaCl. These improvements originated from dynamic barrier effect by crosslinked gel film of PA/PAH and the surface passivation through interface deposition of Ce species.