Subglacial drainage networks and bed composition are leading constraints on basal sliding and ice dynamics. Recent observations have suggested channelized subglacial flow exists beneath Thwaites Glacier, yet it remains unclear if stable channelization is feasible in West Antarctica, where water at the bed is limited. Here, we use the MPAS-Albany Land Ice model (MALI) to run a suite of over 100 subglacial hydrology simulations of Thwaites Glacier across a wide range of physical parameter choices to assess the likelihood of channelization. The model is validated by comparing effective pressure and water thickness fields to previously observed radar specularity content, an indicator of spatially extensive, water-saturated conditions at the bed. Modeled stable channels reliably form within at least 100 km of the grounding line, and commonly reach discharge rates of 50–100 m3 s-1 at the ice-ocean boundary. We then couple a subset of the subglacial hydrology model configurations with the ice dynamics component of the model, using a statistical bed map of till and bedrock locations to assign basal friction coefficients. We find observed ice surface velocities cannot be recreated without accounting for both subglacial channels and spatially variable bed composition. Our results suggest spatially variable bed properties and subglacial drainage morphology are necessary for accurate projections of West Antarctic ice sheet dynamics into the future.