This study reports on the effect of initial curing on corrosion resistance of fly ash (FA) concretes, which was examined through chloride-induced corrosion tests induced by dry and wet cycles. Detailed analysis was carried out on the resistance against ingress of harmful corrosive substances assessed via air permeability tests and cathodic polarization measurements in determining oxygen permeability on embedded steel bars. They were largely affected by the moisture content, the pore structure including pore volume, size distribution and its connectivity which were examined via mercury intrusion porosimetry. In addition, the results showed that the corrosion resistance was observed to be dependent on the availability of calcium hydroxide consumed via the pozzolanic reactions which could affect the initiation of corrosion in the incubation period and the oxygen permeability on embedded steel bars with wet conditions for the early propagation period. Higher resistance against chloride ingress in the FA concrete could be attributed to denser pore structure formed and relatively lower moisture content in the deeper zones especially when cured under dry environment.