Low stability deriving from the accumulation of moisture and intermediates represents the major challenge for practical applications of manganese oxides (MnOx) for ozone elimination. Here, Li+, Na+ and K+ were successfully introduced into the channel framework of amorphous MnOx to improve its stability through a simple post-treatment method. Alkali metal modification can promote the removal of ozone by amorphous MnOx, and Na-MnOx exhibited superior catalytic activity and remarkable stability in water-resistance, cycling and long-term tests. The Na introduction facilitated the formation of oxygen vacancies, and improved low-temperature reducibility and lattice oxygen mobility. The mechanism of ozone decomposition on amorphous MnOx and Na-MnOx catalysts was deeply investigated by in situ diffuse reflectance infrared Fourier transform spectra (in-situ DRIFTS). The Na addition strengthened the hydrophobicity of oxygen vacancies, but also greatly boosted the desorption of intermediate oxygen species and the ozone decomposition cycle.