Abstract Many continental shelves tend to steepen landward. Existing models attribute this curvature to a progressive attenuation of the effect of postglacial seaâlevel rise or sediment redistribution by modern coastalâmarine processes. Here, we present an alternative framework in which shelf curvature arises from an inherent selfâorganizing mechanism. During seaâlevel rise, if the critical length of the downstream alluvial river is exceeded, deltaic sedimentation cannot be sustained. In this nonâdeltaic transgressive regime, the alluvial aggradation rate autogenically increases as the river shrinks, enhancing alluvial sediment accumulation and producing a steeper local shelf slope closer to the shoreline. Twoâdimensional geometric modeling reveals a simple governing equation for the selfâorganized curvature of the shelf profile, with support from flumeâtank experiments and applications to modern systems, providing a mechanistic basis for interpreting existing shelf profiles.