1,5-naphthyridine-based conjugated polymers (P1 and P2) were synthesized and extensively characterized by H-1 NMR, thermogravimetric analysis (TGA), FT-IR. These polymers were employed as co-sensitizers in DSSCs sensitized with Ru (II) based N3 dye. In comparison to the N3 sensitized device, the P1 and P2 co-sensitized solar cells demonstrated enhanced open circuit voltage, (V-OC) of 825 and 788 mV and better fill factor (FF) of 59 and 58%, respectively. The co-sensitization of P1 and P2 with N3 increased the overall efficiencies to 5.88% and 6.21%, respectively, as compared to 5.58% for N3 sensitizer alone. The fabricated device based on N3 co-sensitized with P2 displayed higher charge recombination resistances as compared to the devices based on N3 alone or N3 co-sensitized with P1. The conjugated polymers are believed to enhance light harvesting ability and reduce the charged recombination in the co-sensitized solar cells.