<p>Charge injection, transport and recombination in thin-film organic electronic devices is predicted to be filamentary on the nanoscale owing to energetic disorder. However, direct experimental evidence of this phenomenon has remained elusive. Here we study small molecule organic light-emitting diodes using super-resolution microscopy and find that their electroluminescence is spatially non-uniform at submicrometre length scales. The local electroluminescence intensity varies by up to 30% relative to the mean and flickers stochastically on millisecond-to-second timescales. These inhomogeneities are neither observed in photoluminescence nor polycrystalline organic light-emitting diodes, and differ for the highest- and lowest-energy components of the electroluminescence spectrum. They are consistent with intrinsic nanoscale variation in the local recombination rate induced by static disorder in amorphous thin films and should be present in a range of organic light-emitting diodes and other organic optoelectronic devices. Our observations should lead to improved models of nanoscale charge transport that benefit the design and performance of organic optoelectronic devices.</p>