Cancer is one of the main challenges of global public health and a leading cause of death, hindering the increase in life expectancy, and Leishmaniasis occupies the second position in the number of deaths from parasitic diseases. Gold(I)-based drugs are being studied for chemotherapy and have been shown promising results, leading to the search for analogs with more favorable effect profiles. This work presents the synthesis and characterization of five new gold(I) complexes, [AuIDTCPPh3] and [AuI2DTC(PPh3)2], using dithiocarbamate-derived ligands and triphenylphosphine, with potential biological activity. The antiproliferative activity was investigated in breast tumor cell lines (MDA-MB-231 and 4T1) and a non-tumor breast cell line (MCF-10a), showing that complexation with gold enhances cytotoxic activity. The anti-leishmanial activity was investigated against intracellular amastigotes of Leishmania (Viannia) braziliensis, L. (Leishmania) amazonensis, and L. (L.) infantum. All complexes demonstrated promising activity, especially the bis-gold(I) complexes, which showed higher activity in the studied cell lines and Leishmania parasites. The results show the importance of the gold atom in these compounds, supporting the development of gold-based compounds as prototypes for metallodrugs.