We report the synthesis and properties of new hybrid nanocomposites of poly(3-methylthiophene) and CdSe nanoparticles. The synthesis method is based on the chemical oxidative polymerization of 3-methylthiophene in the presence of CdSe nanoparticles of different shapes (quantum dots, nanorods, and tetrapods). In situ, the open circuit potential and the UV-Vis monitoring of a reaction mixture are used to control the polymerization process. The minimal and maximal CdSe concentrations in nanocomposites are obtained for quantum dots and nanorods, respectively. Nanocomposites are investigated, by using IR, electronic absorption, and photoluminescence spectroscopies, TGA, and DTA. Hybrid photovoltaic (PV) cells based on these materials are fabricated and evaluated. The best PV performance is achieved for a device based on nanocomposites with CdSe nanorods.