A facile approach for synthesizing a carbon quantum dots functionalized multi-walled carbon nanotubes (MWNTs@CQDs) nanocomposite had been carried out through chemical reaction between carboxyl and hydroxyl groups on each surface. The photovoltaic properties of a quantum dots sensitized solar cell (QDSSC) based on the prepared MWNTs@CQDs active material were investigated. The higher conductivity of MWNTs@CQDs, which is considerably higher than a traditional QDs@TiO₂ electrode, allowed the excited electrons to be more effectively transferred from the CQDs to the MWNTs after harvesting photon, resulting in the energy transformed into phonons, and photon losses being comparatively reduced. The photovoltaic conversion efficiency of QDSSC reached its maximum value, ∼1.23%, when the thickness of the MWNTs@CQDs film was 5 ± 0.5 μm. This proposed MWNTs@CQDs nanocomposite had the potential for photovoltaic applications as a QDSSC active material.