The results of theoretical calculations of electronic states of the gallium oxide (Ga2O3) nanocrystals both doped with donor impurity and undoped have been presented in the paper. In the envelope function approximation, the structure, states and energy levels of size quantization in the nanocrystals were determined. According to our calculations, the electron-hole pair forms a bound state of the exciton type in the nanocrystal. The typical donor impurities in Ga2O3, such as silicon and tin, were shown to create bandgap states localized in a spatial domain being several times smaller than the nanocrystal’s volume. Forming a compact neutral pair, the electron and donor ions have no noticeable influence on the states of the optically excited electron-hole pairs. The effect of impurity implantation on recombination processes was also discussed.