Corrosion is a major factor influencing the structural integrity and service life of offshore steel pipe piles (SPPs). This study proposes a zone-dependent corrosion prediction model that accounts for two primary corrosion types: uniform corrosion and pitting corrosion. The uniform corrosion process is described using electrochemical theory, while the pitting corrosion component innovatively incorporates the electric double layer (EDL) theory to calculate the corrosion rate with higher precision. In addition, the wave-induced corrosion acceleration effect is integrated to represent the dynamic marine environment. The proposed model accurately predicts corrosion rates across four typical marine zones—atmospheric, splash, tidal, and immersion—and identifies the splash zone as the most severely affected, exhibiting a corrosion rate of approximately 2.6 mm year⁻¹ under ideal indoor experimental conditions. Furthermore, the influences of temperature and wave characteristics are evaluated to demonstrate the model’s applicability. The results indicate that higher temperatures significantly accelerate corrosion, and wave height exerts the most sensitive effect compared with wave period and wavelength. This study provides a comprehensive framework for predicting zone-dependent corrosion of offshore SPPs and offers theoretical guidance for the service-life assessment and corrosion protection design of marine steel structures.