The plant kingdom is a rich source of compounds with anticancer activities. Curcumin [1,7-bis(4-hydroxy-3- methoxyphenyl)-1,6-heptadiene-3,5-dione] (1) is a secondary metabolite produced by rhizomes of Curcuma longa that has been used for centuries in traditional Medicine in Asia. Anticancer activity is one of the pharmacological properties of curcumin (1) that has been widely explored. Its targets include transcription factors, growth and angiogenesis regulators, apoptosis-related genes, adhesion-related molecules, and cellular signaling molecules. Some curcumin conjugates and metallocomplexes have been synthesized, characterized and evaluated for anticancer activity. In this mini-review, we discuss the mechanism of action by which curcumin (1) inhibits the progression of tumor growth and also the antiproliferative activity of curcumin conjugates and metallocomplexes on human cancer cells. The understanding of how these conjugates and metallocomplexes exert their anticancer activities is essential for future development of effective drugs.