Indium tin oxide films, an important n-type semiconductor oxide, show great prospects in optoelectronic device applications. Consequently, as a key raw material of targets for sputtering films, it is important to prepare low-resistivity indium tin oxide powders. Herein, low-resistivity indium tin oxide submicro-cubes are synthesized by a seed-assisted coprecipitation method. The effects of seed content, In³⁺ concentration, aging time, reaction temperature and calcination temperature on resistivity were investigated by single factor and orthogonal experiments. To ensure reliability and reproducibility of data, each experiment was repeated three times and resistivity of each sample was measured three times to obtain average value. The results indicated that optimal sample was matched with cubic phase In₂O₃. The single-crystal indium tin oxide particles exhibited a regular cubic shape with a size of nearly 500 nm and low resistivity of 0.814 Ω·cm. Compared with particles prepared by the conventional coprecipitation method, indium tin oxide submicro-cubes showed good dispersion. The presence of seed particles provided nucleation sites with lower energy barriers and promoted formation of submicro-cubes. The face-to-face contact among particles and good dispersion contributed to electron transfer, resulting in lower resistivity. The seed-assisted synthesis provides a novel way to prepare low-resistivity indium tin oxide submicro-cubes.