Leishmania braziliensis is one of the pathogenic agents of cutaneous and mucocutanoeous leishmaniasis. There are no validated vaccines to prevent the infection and the treatment relies on drugs that often present severe side effects, which justify the efforts to find new potential antileishmanial drugs. An alternative to promote the discovery of new drugs would be the association of different chemical groups of bioactive compounds. Here we describe the synthesis and bioactivity evaluation against L. braziliensis of cinnamic acid derivatives possessing isobenzofuranone and 1,2,3-triazole functionalities. We tested 25 compounds at 10 μM concentration against extracellular promastigotes and intracellular amastigotes during macrophage infection. Most compounds were more active against amastigotes than to promastigotes. The derivatives (E)-3-oxo-1,3-dihydroisobenzofuran-5-yl-(3,4,5-trimethoxy) cinnamate (5c), (1-(3,4-difluorobenzyl)-1H-1,2,3-triazol-4-yl)methyl cinnamate (9g), and (1-(2-bromobenzyl)-1H-1,2,3-triazol-4-yl)methyl cinnamate (9l) were the most effective presenting over 80% toxicity on L. braziliensis amastigotes. While compound 5c is a cinnamate with an isobenzofuranone portion, 9g and 9l are triazolic cinnamic acid derivatives. The action of these compounds was comparable to amphotericin B used as positive control. Ultrastructural analysis revealed that 5c-treated parasites showed impaired cytokinesis and apoptosis triggering. Taken together, these results highlight the potential of cinnamic acid derivatives in development of novel anti-leishmanial drugs.