The El Niño–Southern Oscillation (ENSO) substantially influences seasonal Atlantic tropical cyclone (TC) activity by impacting environmental conditions important for TC genesis, including vertical wind shear and relative humidity. However, the influence of future climate change on the teleconnection between ENSO and Atlantic TCs is uncertain, as climate change is expected to affect both ENSO and overall conditions for TCs. This study used the Weather Research and Forecasting (WRF) model configured on a tropical channel domain to simulate Atlantic TC seasons in historical and future climates under different ENSO conditions. Each experiment consisted of 5 ensemble members, was run from June to December to represent an Atlantic TC season, and was forced with idealized sea-surface temperature (SST) configurations. The SST configurations include the following patterns under each historical and future climates: monthly-varying climatology, Central Pacific El Niño, Eastern Pacific El Niño, and La Niña. The SST forcings were created based on simulations from the CESM1 Large Ensemble Project, with ENSO events identified using the ENSO Longitude Index (ELI). We found that the different types of El Niño have different impacts on seasonal Atlantic TC activity in the historical simulations; for example, there were fewer Atlantic TCs during Eastern Pacific El Niño compared to Central Pacific El Niño, in agreement with other studies. The change in vertical wind shear had a greater influence on the Atlantic TC response compared to the change in relative humidity. For each ENSO state, the future simulations produced a decrease in the number of Atlantic TCs, relative to the corresponding historical simulation, in association with an increase in vertical wind shear. These findings have important implications for understanding future TC impacts and for using ENSO for seasonal TC prediction into the future.