In this study, the antimicrobial and nonlinear optical (NLO) response of thiosemicarbazone, semicarbazone, and their organotin(IV) compounds have been investigated. Organotin(IV) complexes of various types, namely [R2Sn(PhTscz)2], [R2Sn(Tscz)2], [R2Sn(Scz)2], [Bu3Sn(PTscz)], [Bu3Sn(PTscz)], and [Bu3Sn(Scz)] (where R = n-Butyl; methyl; PhTsczH = (±) 2-isopropyl-5-methyl-cyclohexylidene)-N-phenylhydrazine-carboxamide, TsczH = (±) 2-isopropyl-5-methylcyclo-hexylidene)hydrazinecarbothioamide, SczH = (±) 2-isopropyl-5-methylcyclohexyli-dene)hydrazine-carboxamide), were synthesized and characterized by CHN analysis, molar conductivity, UV-Vis, FTIR, and NMR (1H, 13C, 119Sn) spectroscopy, along with theoretical evidence obtained through density functional theory (DFT) simulations. The results showed that the Schiff base (HL) ligands acts as a bidentate NO/NS donor with azomethine nitrogen (N) and deprotonated ketonic oxygen/thionic sulphur (O, S) atoms. [R2Sn(L)2] complexes are assigned a distorted octahedral structure, while Bu3Sn(L) complexes have distorted trigonal bipyramidal structures. The B3LYP/LanL2DZ programme theoretically discussed the electronic structure and nonlinear optical (NLO) properties of the synthesized compounds. The synthesised compounds were evaluated for antibacterial activity using the zone inhibition method. Antibacterial activity of the ligands and its metal complexes against Gram(+) and Gram(-) bacteria demonstrated that the organotin complexes are more potentially resistant to microbial activities than the free ligands. According to the reactivity parameter factors, compound Bu2Sn(Scz)2 (3) is less reactive and more stable. Nonlinear optical (NLO) study revealed that compound (3) had greater linear polarizability (α) values, whereas compound Me2Sn(Scz)2 (9) had higher first hyperpolarizability (βtot) values of 244.29 a.u. Because of their high initial hyperpolarizability values, these molecules have excellent non-linear optical properties and can be exploited as innovative materials in the construction of optoelectronic devices.