In this study, a significant improvement of deep-red luminescence was successfully achieved via the substitution approach in the M n ⁴⁺ -activated C a _14-x K _x A l ₁₀ Z n ₆ O ₃₅ phosphor. The optimal M n ⁴⁺ doping level x was determined by studying luminescence concentration quenching behavior. The measured photoluminescence (PL) spectrum showed five distinct vibronic structures with the main peak centered at 712 nm. A theoretical simulation work was conducted for comparison, and the predominant phonon mode involving in the vibronic transition process was revealed. From the temperature-dependent PL spectra, an abnormal luminescence enhancement was observed at the temperature rising from T =100 to 340 K, and the underlying phonon-assisted luminescence mechanism was theoretically disclosed. Finally, we studied the temperature-dependent luminescence lifetime, and the primary phonon energy in the vibronic behavior was identified from the fitting work.