In this work, we have extracted natural dye from the pericarp of Mallotus phillipensis (kamala tree) fruit which is commonly found in East Asia. The natural dye extract has been used such a photosensitizer for dye-sensitized solar cells. Density Functional calculations on one of the major constituent natural dye rottlerin, have been performed to check the properties and applicability of the proposed dye as a photosensitizer and manifested high electron injection efficiency. The best performing device exhibited a power conversion efficiency of 0.55% under 100 mW/cm 2 . This kind of non-toxic and biodegradable natural dye can easily be extracted from an inedible source using a very low-cost technique and therefore it can provide the best alternative to the synthetic dye for solar cells.