The Turkana Basin, part of the East African Rift System (EARS), exhibits a complex extensional regime with ongoing rifting and crustal thinning. Our work pushed the limits of geodynamic modeling to quantify the presence of an extension-catalyzing mantle plume beneath the study area’s subsurface. Sensitivity testing with variation in stress, strain localization, temperature, and viscosity gradient allowed us to create a suite of 2D thermomechanical simulations that constrained rifting and mantle plume geometry.