Synthesis and biological evaluation of unsymmetrical curcumin analogues (UCAs) have been achieved. Tyrosinase inhibitory activities were found for most of the prepared synthetic UCAs. Among them, compounds containing 4-hydroxyl-substituted phenolic rings with C-2/C-4- or C-3/C-4-dihydroxyl-substituted diphenolic rings were more active (IC(50) = 1.74~16.74 μM) than 4-butylresorcinol and kojic acid, which suggested that the 4-hydroxyl groups in UCAs play a crucial role in tyrosinase inhibitory activities. The inhibition kinetics analyzed by Lineweaver-Burk plots revealed compounds 3c and 3i containing catecholic rings were mixed-competitive inhibitors, whereas compounds 3d and 3j containing resorcinolic rings were competitive inhibitors. The preliminary evaluation results of acute toxicity showed the representative 3d and 3j were non-toxic in mice dosed at 1,200 mg/kg. This research suggests that, with the advantage of being readily prepared small molecules, polyphenolic UCAs have the potential to develop into pharmacological inhibitors of tyrosinase.