In this paper, a comprehensive mathematical model was developed in order to estimate the instantaneous biocorrosion pit depth and shape on steel structures in sulfate-reducing bacteria (SRB) environments. The SRB cathodic depolarization theory was adopted as the SRB-influenced biocorrosion mechanism. The model was applied to marine, landfill, and freshwater environments. The comprehensive feature of the model made it possible to predict the pitting biocorrosion growth rate and the pit depths and shapes in each of the above environments. The model results were found to be in reasonable agreement with the experimental data found in the literature under the identical conditions.