The coexistence of different metal cations in single crystal structure may improve electron transfer rate and catalytic activity. Hence, a series of iron‐doped nickel selenide nanoparticles were engineered by adjusting the iron amount as counter electrodes (CEs) in dye‐sensitized solar cells. By contrast, the as‐designed iron‐doped nickel selenides possess more excellent electrochemical properties than the pure nickel selenides. In particular, 10% Fe‐Ni0.85Se achieves the lowest charge‐transfer resistance and highest electrocatalytic performance, outperforming that of Pt. As expected, based on the optimal 10% Fe‐Ni0.85Se CE, the dummy dye‐sensitized solar cell yields a higher power conversion efficiency of 8.57% compared with that of 15% Fe‐Ni0.85Se (8.33%), 5% Fe‐Ni0.85Se (8.15%), Ni0.85Se (7.89%), and even Pt CEs (8.04%).