Three-dimensionally ordered macroporous (3DOM) LaMnO₃ oxides with tunable oxygen vacancies have been successfully fabricated via a facile nitric acid-aided modulating sol–gel method. The morphology, composition, pore structure and reducibility of the prepared catalysts were characterized by XRD, EDS, FE-SEM, XPS, TPR, and N₂ adsorption–desorption. The results indicate that the oxygen vacancies contents of the as-prepared catalysts are heavily dependent on the amount of nitric acid. Among the three LaMnO₃ catalysts, the LaMnO₃-C sample shows the highest oxygen vacancies content and the better low-temperature reducibility. These findings reveal that the introduction of a little amount of nitric acid can effectively promote the formation of oxygen vacancies, ultimately resulting in an enhanced catalytic oxidation activity for ethyl acetate oxidation.