The emission properties of the rare earth (RE) elements have been found to be sensitive to the local lattice environment around them, and could be employed for probing the local lattice environment. Because each constituent ion of a material should have its own particular structural environment, the emission profiles in RE elements depend strongly on the doping sites of RE elements inside the host crystals. We investigated the emission properties of the Eu3+ ion doped BaZrO3 (BaZrO3:Eu) with doping site dependence (A-site vs. B-site), as well as ambient dependence in the post-annealing process. The site-selective doping was identified from the Rietveld refinement analysis on the XRD patterns of our BaZrO3:Eu samples. Photoluminescence and photoluminescence excitation measurements showed that the emission properties of the samples with the Eu3+ ions substituted at Zr sites revealed much greater emission properties than those at the Ba sites. This behavior was found to accord with the change in intensity ratio of D-5(0) -> F-7(0,2) to D-5(0) -> F-7(1) in Eu ions, which should be a measure of the local lattice asymmetry around the Eu ions. We also found that with post-annealing in H-2 atmosphere, the emission intensities of the Eu ions increased significantly, while with post-annealing in O-2 atmosphere, they were suppressed. Our findings indicated that the cation/oxygen vacancies could change the local lattice environment around the Eu ions, as well as the valence states of Eu ions, depending on the doping site in the cubic perovskite.