Electrides have promising applications for catalysis and electronics due to the presence of anionic electrons, defined as electrons that trapped in cavities and serve as the counter anions to positive charges in a crystalline lattice. The stability with respect to temperature, moisture, or oxygen, remains a bottleneck for electrides. Mayenite electride can be thermally stable up to 400 °C under ambient conditions. Cation-doped derivatives of mayenite electride emerged in recent years to improve its electron density, electrical conductivity, or catalytic activity. However, the effects of cationic doping on thermal stability of mayenite electride remained unknown. To provide an insight in this regard, Cu-doped mayenite electride was fabricated via spark plasma sintering in this work. Characterization of the structure, electrical conductivity, and oxidation behavior showed that Cu-doping improved the thermal stability of mayenite electride by increasing the oxidation onset temperature with reduced oxidation rates, as well as decreasing the lattice parameter.