<p>Advancing clean energy technologies demands efficient and durable electrode catalysts for solid oxide cells (SOCs). Despite their exceptional catalytic properties, Pt-based materials face critical challenges in high-temperature applications owing to particle agglomeration and cost constraints. Here, we demonstrate a rational design strategy utilizing controlled in situ exsolution to create strongly anchored PtSn nanoalloys on oxygen-deficient PrBaMn_1.8Pt_0.1Sn_0.1O_5+<i>δ</i> (L-PBMPtSn) perovskite oxide. Through precise compositional engineering and structural control, we achieved a uniform dispersion of PtSn nanoparticles with unique socket-like interfaces that prevent agglomeration while maintaining high catalytic accessibility. The optimized electrode demonstrates remarkable bifunctional performance, achieving a current density of 1.6&#xa0;A cm⁻² at 1.8&#xa0;V for CO₂ electrolysis and a maximum power density of 316&#xa0;mW cm⁻² for fuel cell operation at 800&#xa0;°C. More significantly, the electrode exhibits exceptional stability with only 9.6% performance degradation over 100&#xa0;h of operation, which is a substantial improvement over conventional electrodes. Our findings establish a new paradigm for designing high-performance SOC electrodes through the controlled exsolution of precious metal alloys, offering broader implications for catalyst design in high-temperature electrochemical systems.</p> Graphical abstract <p></p>