Thermal self‐focusing of laser light may be significant when a plasma is irradiated with short‐wavelength laser light. Self‐focusing magnifies the light intensity which can increase absorption by plasma waves (producing hot electrons which may cause preheat), could increase scattering, and could be a perturbation source for the Rayleigh–Taylor instability. We use two‐dimensional hydrodynamic simulations to characterize thermal self‐focusing for parameters of interest to laser fusion applications, and present a simple model. A diverging beam is shown to reduce the self‐focusing.