The effects of geranic acid and its structurally related derivatives (geraniol, citronellic acid, and citronellol) on cell viability and melanin biosynthesis in Melan-a cells were evaluated in this study. Among them, geranic acid evidenced the strongest inhibitory activity on melanin production, coupled with low cell toxicity. Treatment with 500 μM of this compound resulted in a reduction in melanin content of 35.4% as compared to the live cell percentage (91.7%). Moreover, geranic acid also inhibited tyrosinase activity and intracellular tyrosinase expression in a dose-dependent manner. These results show that geranic acid may function as a skin depigmenting agent via the inhibition of tyrosinase activity and expression within melanocytes.