The present work describes the use of gold nanoparticles as an efficient drug delivery vehicle to target skin melanoma cells B16F10 by photodynamic cancer therapy. For the first time, gold nanoparticles were synthesized from medicinally important plant Decalepis hamiltonii. The nanoparticles were further conjugated with an anticancer drug 5-aminolevulinic acid (5-ALA) and subsequently activating the photosensitizer molecule protoporphyrin IX (PpIX) through irradiation which resulted in the formation of reactive oxygen species. The roots of Decalepis hamiltonii was used for the synthesis of gold nanoparticles by a simple technique of reduction reaction and the morphology like size, shape, charge were evaluated using SEM (Scanning Electron Microscopy), DLS (Dynamic Light Scattering) and Zeta potential analysis. The cytotoxicity of nanoparticles were tested on RBCs and buccal cells which showed there was negligible damage to the cells. The photodynamic therapy was tested on skin melanoma cells and the results were compared with the standard drug 5-ALA and production of ROS molecules was evaluated using 2,7 dichlorofluorescein-diacetate (DCFH-DA) probe. The results indicated that the gold-5ALA conjugates had a deleterious effect on cancer cells specially after activation of protoporphyrin IX and showed a two fold increase in cytotoxic level post irradiation. Interestingly, the gold nanoparticles and conjugates which showed high cytotoxicity against cancer cells had no significant effect on normal RBCs and buccal cells indicating there was a specific target on cancer cells.