Climate change is projected to increase growing season length and temperature in Canada but how soybean [Glycine max (L.) Merr.] will respond is uncertain. By modelling soybean responses to climate change scenarios, stakeholders can develop adaptation strategies. The CSM-CROPGRO-Soybean and STICS models were used to simulate soybean responses under baseline (1971–2000) and in near (2041–2070) and distant (2071–2100) future climate scenarios, including those resulting in altered seeding dates in eastern Canada. Field data collected in Ottawa were used to evaluate the models. The simulated seed yield using the CSM-CROPGRO-Soybean model showed an increase of about 14% (0.34 t ha^-1) in the near future and a decrease in the distant future under RCP8.5 and the STICS model estimated a decrease in both the near and distant future. When the crop parameters determining the life cycle were increased by 30% and 40%, the simulated seed yield increased by more than 5%–10% and 10%–20% and by more than 20%–30% and 27%–40% if combined with current harvest index levels. Our simulations showed that soybean seed yield would not benefit from a prolonged growing season under the projected future climate in eastern Canada, unless harvest index is maintained.