Coatings for structural steel have been developed over the years to extend the service life of highway bridge structures by improving its corrosion durability and minimizing maintenance requirements. Nanoparticles are being considered in the development of durable coating systems due to their beneficial electrical and mechanical properties. The present study aims to investigate the corrosion performance of a nanoparticle enriched zinc rich primer (NPE-ZRP) for structural steel in aggressive marine exposure. Test parameters included introduction of local coating defects to expose the steel substrate and exposure to chloride environments. To evaluate the coating performance, samples were exposed to harsh outdoor marine environment as well as immersion in 3.5% (w/w) NaCl aqueous solution. Surface discoloration was observed for the samples in all exposure. Unscribed samples showed good corrosion protection whereas moderate surface rust was observed for scribed samples after exposure. After an initial period of high corrosion activity, consumption of the exposed zinc at the scribed region continued at a slow rate without the incremental rust formation. That would indicate zinc activity and some level of beneficial cathodic polarization. Good coating bond strength and barrier protection was observed. Further assessment of the effect of nanoparticles on the galvanic coupling of dispersed zinc pigments and impact on the long-term durability of NPE-ZRP coating is in progress.