Abstract Slip distribution along tectonic faults is recognized as highly heterogeneous across all spatial scales and is linked to various aspects of the earthquake cycle, such as aftershock density and stress‐drop variability. A key factor often considered to control slip heterogeneity is the fault geometry, which is typically nonplanar at various scales, yet experimental validation of theoretical models is lacking. We present high‐resolution measurements of slip from controlled laboratory earthquakes along interfaces with various geometries, from simple double‐bends to self‐similar rough faults. We find that local slip gradients are proportional to fault curvature. For rough faults, we show both experimentally and analytically that slip exhibits a fractal character that is, scaled by a power law, although with a different exponent than the fault geometry. These results provide the first experimental evidence that slip variability can be predicted from known fault geometry, offering new insights into the mechanical processes governing earthquake rupture.