A variety of pentavalent antimonials have been synthesized from the triorganoantimony(V) halides and a variety of carboxylic acids having known biological applications to better understand the medicinal potential of the synthesized assemblies. The successful synthesis of complexes 1A-18A, 1B-10B and 1C-20C was confirmed by melting points, elemental analysis, FTIR, 1H & 13C NMR spectroscopy. The selected finely crystallized complexes have also been analysized through single crystal X-ray diffraction technique. The crystallographic analysis reveals that these complexes are mononuclear in solution as well as in solid state. The carboxylate ligands bind to the antimony(V) atom through oxygen atoms and occupy axial position adopting geometries between distorted trigonal bipyramidal and square pyramidal. Main purpose objective of this study was to investigate anti-leishmanial and cytotoxic/anticancer potential of the synthesized pentavalent antimonials bearing carboxylic acids with a variety of pharmacophores. The activity of these compounds was tested against Leishmanial tropica and human cell lines carcinomas A498 (renal), EVSA-T (breast), H226 (lung), IGROV (ovarian), M19 (melanoma-skin), MCF-7 (breast), WIDR (colon) and MDA-MB-231 and HeLa. Results of biological activities including anti leishmanial and anti-cancer activity demonstrated that the compounds under studies significantly inhibit Leishmania parasite and also showed promising anti-cancer activity. The carboxylic acids showed no considerable results, while p-tolyl (1B-10B) and 2,5-dimethylphenyl (1C-20C) moieties bearing complexes exhibited potent activity compared to the simple phenyl derivatives (1A-18A). The studies also reveal that these compounds have considerable shelflife, reproducibility and stability in solution mediums as used for testing of biological activities. Hence, it is suggested that reported pentavalent antimonials, particularly with p-tolyl and 2,5-dimethylphenyl groups seem to be a safe, reasonable and worthwhile option for the further investigations to hunt the lead therapeutic agents for leishmaniasis and cancer.