The in situ gelation that utilizes the dissolution of polymers inside the cell is allowed high concentration polymer gel without concerns regarding high viscous electrolyte incorporation into the cell as in the conventional approach. We demonstrate the in situ gelation of polymer composite electrolytes using poly(vinylidene fluoride) nano spheres (PVdF NSs). The PVdF NSs were synthesized by high pressure emulsion polymerization using gaseous vinylidene fluoride monomers. Compared to the liquid electrolyte (LE) DSCs without PVdF gelation, the PVdF polymer gel electrolyte (PGE) DSCs displayed higher eta than the LE DSCs; specifically, the 10 wt % PVdF PGE DSCs display 8.1% of the eta, while the LE DSCs only display 6.5%. We characterized the effect of PVdF PGE on the photovoltaic parameters in detail. We also compared the long-term stability of DSCs containing LE and PVdF PGE. The DSCs with PVdF PGE exhibited high stability compared to the LE DSCs, similar to a conventional PGE system. We believe that this facile in situ gelation approach could be utilized for not only the practical application of polymer gel electrolytes DSCs but also for various energy-storage devices.