Design of light harvesting systems using inorganic−organic hybrid nanostructures is an emerging field of research. Here, we design hybrid nanostructures by using electrostatic attraction of negatively charged CdTe QDs with positively surface functionalized poly[2-methoxy-5-(2-ethylhexyloxy)- 1,4-phenylenevinylene] (MEHPPV) polymer nanoparticles for developing an efficient light harvesting system. Interfacial charge transfer between QDs and polymer nanoparticles has been investigated by ultrafast spectroscopy which is crucial for designing an efficient light harvesting system. Interfacial charge transfer dynamics are being controlled by tuning the size of QDs which is eventually controlled by highest occupied molecular orbital (HOMO)−lowest unoccupied molecular orbital (LUMO) levels of QDs. Femtosecond fluorescence upconversion and transient absorption spectroscopic studies reveal that the hole transfer process takes place from QDs to polymer nanoparticles and the rate of hole transfer process is size dependent on QDs. The fundamental understanding of the charge transfer dynamics opens up new possibilities to design an efficient light harvesting system based on an inorganic−organic hybrid system.