Reflective paint, fabricated from dye and pigments, has attracted considerable attention given its easy production and various applications. In this work, in a rapid process, we produced highly diffuse reflective white paint based on barium sulfate as a pigmented diffuse reflector (PDR) with 99% reflection to be used as the back surface reflector solar cells. Employing barium sulfate as pigments paves the way for fabricating cost-effective reflective paints with high durability and UV resistance. The paint was applied on the back surface of the counter electrode in a TiO2 nanoparticle-based dye-sensitized solar cell (DSC) which improved the power conversion efficiency (PCE) from 3.47% (in the absence of any reflective layer) to 4.78% (in presence). The developed BaSO4 highly diffuse reflective paint can be applied to a wide range of substrate materials with different methods for various applications.