Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its merits on clean, low cost, high efficiency, good durability, and easy fabrication. However, the commercial application of DSSCs has been hindered by the high expenses of counter electrodes (CEs) and limited power conversion efficiency. With an aim of significantly enhancing the power conversion efficiency, here we pioneerly synthesize CoPt alloys using an electrochemically codeposition technique which are employed as CEs for DSSCs. Owing to the rapid charge transfer, electrical conduction, and electrocatalysis, power conversion efficiencies of CoPt-based DSSCs have been markedly elevated in comparison with the DSSC using Pt CE. The DSSC employing CoPt0.02 alloy CE gives an impressive power conversion efficiency of 10.23%. The high conversion efficiency, low cost in combination with simple preparation, and scalability demonstrates the potential use of CoPt alloys in robust DSSCs.