There continues to be substantial uncertainty about the Earth’s equilibrium climate sensitivity. This uncertainty is a key contributor to uncertainty in global temperature projections, though its role in sea-level projections is relatively under-examined. Here, we investigate the impact of climate sensitivity on sea-level projections in a probabilistic modeling framework, focusing on the extreme upper tails. We couple the reduced-complexity climate model, Hector, to a semi-empirical sea-level modeling framework, BRICK, creating a jointly probabilistic calibration of key climate and sea-level related parameters to historical observations. From this joint calibration, we isolate parameter sets with high versus low climate sensitivity. We investigate the range of global sea-level projections produced from these different climate sensitivity bins. We also explore the effect of climate sensitivity on sea-level rise time horizons and spatial patterns of sea-level change. Our results indicate that Earth’s future sea level depends substantially on its climate sensitivity, and this dependence is stronger for more extreme sea-level rise scenarios.