Life-cycle reliability of reinforced concrete (RC) structures under chloride-induced corrosion is generally evaluated using diffusion models based on Fick's second law. While the analytical solution for one-dimensional (1D) diffusion is frequently used to compute the chloride concentration at concrete cover depth, two-dimensional (2D) diffusion models are more accurate to describe the actual chloride transport in RC structures. This paper is aimed at quantifying the influence of different diffusion models on the accuracy of time-variant reliability analysis of RC structures suffering chloride-induced corrosion. A RC cross-section is considered as a case study and the analytical solution of 1D diffusion is compared with the 2D numerical solution obtained using cellular automata. Reliability analysis is finally conducted by investigating different exposure conditions and multiple limit states, including corrosion initiation, concrete cover spalling, and attainment of cracking and ultimate resisting moments