Selective formation of monodisperse spherical vaterite calcium carbonate (CaCO3) precipitate using glycine (Gly) in a calcium hydroxide (Ca(OH)2)-carbon dioxide (CO2) reaction system at room temperature and atmospheric pressure is reported. Crystalline products were examined by scanning electron microscopy, powder X-ray diffraction, Fourier transform infrared spectrometer, Raman spectra and laser particle size analysis. The experimental results suggest that increasing Gly concentration caused inhibition of the nucleation and growth of calcite and promoted the formation of vaterite. By adjusting the content of additive Gly, the crystalline product was almost monodisperse spherical vaterite CaCO3. The resulting product had good thermal stability, still keeping its crystal type, spherical shape, and size after being heated above 350 °C. Mechanism studies illustrated that the complex effects between Gly and Ca2+ played the key role in the formation process of monodisperse spherical vaterite CaCO3. Further studies indicated that this method might also apply to other reaction systems, such as CaCl2-NH3·H2O-CO2 and CaCl2-Na2CO3 reaction systems. These studies are paving the way for industrial preparation and further commercial applications of monodisperse spherical vaterite CaCO3.