The hole-blocking and electron- transporting layer is an important component of third-generation solar cells. This layer is responsible for both hindering the hole recombination from the hole-transport layer and collecting photo-generated electrons; that in turn impact photon-to-current conversion efficiency (ɳ) of devices. Conventionally, WO₃ is being used as hole-transport layer owing to high work function and carrier mobility; and excellent thermal stability. In this paper we report ultra-thin WO₃ films,prepared by UVO-treatment of WO₃-octadecylamine Langmuir-Blodgett multilayers, for use as blocking layers in dye sensitized solar cells (DSSCs). For the first time, it is observed that ɳ of DSSCs with optimized WO₃ blocking layer improved significantly (21%) as compared to those based on conventional TiO₂ blocking layers. The improvement in ɳ is the result of improved short-circuit current density which is obtained without any accompanying reduction in open-circuit potential and fill factor. This is attributable to the dense and uniform morphology, excellent hole-blocking properties, crystallinity and proper position of Fermi level. The analyses not only reveal that ɳ of DSSCs can be enhanced by employing ultrathin WO₃ LB films as blocking layers but also suggest that the films can possibly be extended further for perosvskite and polymer solar cells.