Chemical deposition is widely used to enhance the performance of perovskite anodes for solid oxide fuel cells (SOFCs). However, the anodes thus produced still have unsatisfactory activity and experience reproducibility problems. For the first time, this paper reports that the in situ exsolution of nano-Ni could be facilitated on Ni-doped (La_0.7Sr_0.3)CrO₃ (LSCNi) anodes with A-site deficiency, showing a maximum power density of 460 mW cm⁻² in 5000 ppm H₂S–H₂ compared to only 135 mW cm⁻² of fuel cells with stoichiometric LSCNi. Besides, the fuel cell also demonstrates desirable redox stability in sour fuel. The introduction of A-site deficiency can help the formation of highly mobile oxygen vacancies and remarkably enhance the reducibility of Ni nano-particles, thus significantly increasing electronic conductivity and catalytic activity simultaneously. Such fabricated perovskite has the potential to be decorated with diverse nano-active particles for a wide range of applications in industrial fields.