BaBiO3 is an insulator with perovskite structure. While the hole doping of BaBiO3 has been achieved long ago, its electron doping has not been realized yet because trivalent La ions, for example, tend to substitute for tetravalent Bi ions in B sites rather than divalent Ba ions in A-sites. We have used thin film synthesis to substitute La ions for Ba ions in BaBiO3; we first deposit, on a substrate, a buffer layer of BaBiO3 to overcome the lattice mismatch and then deposit a triple unit of a monolayer of Ba-deficit BaBiO3, the necessary amount of La2O3 to fill in the A-site vacancies, and lastly a monolayer of pure BaBiO3. This triple unit of Ba-deficit Ba1−xBiO3/La2O3/pure BaBiO3 is repeated several times for a certain thickness sample, and then the whole structure is treated thermally at 550 °C. Scanning TEM image analysis confirms that La ions go indeed to the A-sites and La doped BaBiO3 remains in perovskite structure. It is found that La substitution for Ba in BaBiO3 causes the Raman peak related to the breathing mode of BaBiO3 to decrease in intensity as a function of the doping level. Dielectric measurements of La doped BaBiO3 also reveal an upward shift in temperature and associated relaxation behaviors for the octahedral tilt-driven structural transition which occurs at Tc ∼ 140 K for pure BaBiO3.