The burgeoning maintenance backlogs in Canadian bridge infrastructure underscores the need to adopt Prefabricated Bridge Elements and Systems (PBES) as a means of relieving this burden. PBES can offer substantial time and cost savings for repairs and replacements. Among the key contributors to a bridge's seismic behaviour is the substructure PBES, with a particular focus in this paper on the precast column-to-pile shaft assembly as a substructure PBES type. Climate change-induced structural deterioration is accelerating, introducing significant uncertainties into the seismic performance of aging bridge substructures. The combined impacts of climate change, deterioration, and seismic activity on the precast column-to-pile shaft assembly have thus far received limited investigation. The objective of this current paper is to assess the impact of corrosion on the seismic performance of precast column-to-pile shaft assemblies, taking into account the influence of climate change. To achieve this, key design parameters were initially determined to assure the formation of a plastic hinge at the column's base during seismic events, while maintaining the elasticity of the pile shaft. The effectiveness of the seismic design was verified through moment-curvature analyses and finite element simulations. The effects of climate change on corrosion, including early initiation and accelerated material degradation, were incorporated into the corrosion model, considering environmental factors like temperature and relative humidity. The degradation mechanisms in both columns and pile shafts, such as loss of reinforcement section and material property degradation were modelled. Finally, the analysis findings were synthesized to inform the climate change impacts on the time-dependent seismic resistance, including variations in moment strengths and failure modes.