Highway bridges form an integral and important part of a nation’s infrastructure. Estimation of the seismic vulnerability of these bridges is a necessary step to identify the associated risk and ensure the safety of lifeline systems. Reinforced concrete (RC) dominates bridge construction around the world (along with prestressed concrete). Corrosion has been identified as a major degrading factor in concrete bridges, which makes these structures more vulnerable to extreme event loads, such as earthquake or wind forces, over their design life. Seismic vulnerability assessment of bridge structures is typically performed through a seismic fragility analysis in the probabilistic domain. For about two decades, researchers have been using this tool to effectively estimate the seismic failure probabilities of bridge structures. More recently, researchers have focused on the seismic fragility estimation for concrete bridges deteriorating primarily due to corrosion. However, most of these studies have not properly dealt with (i) the significant uncertainties in the corrosion process and (ii) the effects of pitting corrosion. The current paper presents a unique framework of seismic fragility estimation of corroded concrete bridges, incorporating a probabilistic treatment of the non-uniform corrosion process and integrating it with the Bayesian updating of the corrosion model based on monitored data (measurements through non-destructive testing). The time-varying seismic fragility of a RC bridge pier is estimated in an illustrative numerical example. Conclusions are drawn based on how the seismic fragility for this bridge column vary over time and on the effectiveness