The first observation of strongly tunable electroluminescence from a new type of semiconductor superlattice is reported. We achieved a shift of the electroluminescence peak energy by several hundred millielectron volts below the gap of pure GaAs, when electrons and holes are injected over long distances via selective electrodes. This directly reflects the tunability of the indirect gap in real space, which is a unique feature of doping superlattices. The results further demonstrate that with increasing doping concentration of the constituent superlattice layers the luminescence frequency can be tuned over an even wider range. This behavior agrees well with our calculations.