AbstractTotten Glacier (TG), the primary ice discharger of East Antarctica, contains 3.85 m sea level rise equivalent (SLRe) ice mass and has displayed ocean‐driven dynamic change since at least the early 2000s. We project TG's evolution through 2100 in an asynchronously coupled ice‐ocean model, forced at the ocean boundaries with anomalies in CMIP6 projected temperature, salinity, and velocity. Consistent with previous studies, the Antarctic Slope Current continues to modulate warm water inflow toward TG in future simulations. Warm water (−0.5 – C) accesses TG's sub‐ice shelf cavity through depressions along the eastern ice front, driving sustained retreat of TG's eastern grounding zone that cannot be captured in uncoupled models. In high emission scenarios, warm water overcomes topographic barriers and dislodges TG's southern grounding zone around 2070, increasing the rate of grounded ice loss 3.5‐fold (10–35 Gt/yr) and resulting in a total 4.20 mm SLRe loss by 2100.