Perovskite (ABO3) materials are commonly used as cathodes for solid oxide electrolysis cells (SOECs), but their electrochemical performance is poor due to the low CO2 adsorption and conductivity. Herein, we design an A-site deficient (La0.5Sr0.5)0.95Fe0.85Mn0.1Ni0.05O3-δ (95LSFMNi) perovskite cathode with rich oxygen vacancy and Ni–Fe alloy to enhance the CO2 adsorption. The surface precipitated Ni–Fe alloy nanoparticles introduce more oxygen vacancies into the matrix and increase the active sites for CO2 adsorption, enhancing the electrochemical reduction reaction for CO2 (CO2RR). Fe element exsolution was stimulated after the Ni reduction, and Fe content in the nanoparticles increased with the reduced time. The 95LSFMNi with in-situ dissolved Ni–Fe particles exhibits a doubled conductivity than the parent La0.5Sr0.5Fe0.9Mn0.1O3-δ (LSFM) at 800 °C and 5%H2/Ar. In addition, the electrolysis current density at 1.6 V and 800 °C reaches 1.09 A cm−2, representing a 28.2% increase compared to the LSFM. These findings demonstrate that the in-situ precipitated nano Ni–Fe particles are highly effective in enhancing the catalytic ability of CO2RR.