Na+ was incorporated into red-emitting CaMoO4:Eu3+ phosphor to form solid solutions and reduce the crystal symmetry. For a fixed Eu3+ concentration, the luminescent properties as a function of Na+ concentrations were systematically studied under near-ultraviolet (UV) excitation. Enhanced red emission at 613 nm was observed and the strongest intensity was 4.5 times that of the sample without Na+. Differing from the charge-compensation mechanism, this enhancement was related to the structural distortion and decreasing centrosymmetry. The increased ratios of red emission (5D0 → 7F2) to orange (5D0 → 7F1) in intensity revealed that the structural adjustment was achieved in the phosphors via the incorporation of Na+.