The effects of multi-walled carbon nanotubes (MWCNTs) in ZnO films as an active layer of dye-sensitized solar cells (DSSCs) have been studied. The ZnO particles and MWCNTs were directly mixed at different concentrations. The composite films were characterized in terms of the structural, optical and photovoltaic properties. Scanning Electron Microscopy (SEM) have illustrated that large agglomerates of ZnO particles at a high MWCNT content (>0.1%) led to a decrease inabsorbing surface area. The active surface area of ZnO-MWCNT films has been confirmed by dye absorption-desorption measurements by means of optical absorption spectroscopy. The maximum dye absorption intensity was found at the concentration of 0.05 wt.% MWCNTin the composite films. The composite films have been used as a working electrode for DSSCs. Compared to the conventional DSSCs with ZnO electrodes, the photocurrent-voltage (J-V) characteristics of 0.05 wt% ZnO-MWCNTs film showed an increase in the short-circuit photocurrent (Jsc) of 32 % leading to an increase in overall solar conversion efficiency (η) by a factor of approximately 1.4.