A novel resorcynyl-1,3,4-thiadiazole-based Zn(II) complex NTBD-Zn was synthesized and characterized via both experimental and computational studies. The research involved detailed absorption and emission properties measurements and simulations, combined with geometric and electronic structure analyses considering different coordination modes of the metal to the ligand. These studies were further complemented by an assessment of the complex’s potential microbiological activity. The additional UV-Vis absorption intensity centered at ca. 370 nm along with the corresponding emission signal at ca. 460 nm observed for NTBD-Zn vs. NTBD attests to a successful complexation of Zn(II) to the resorcynyl-thiadiazole ligand, which, as confirmed by the calculations, occurs preferentially through one of the nitrogen atoms in the thiadiazole ring and the deprotonated ortho-hydroxyl group in the resorcynyl fragment, with the planar arrangement of the resorcynyl-thiadiazole and an only slightly more favored tetrahedral/pyramidal Zn(II) coordination sphere, preference for which increases upon inclusion of a water molecule in NTBD-Zn. The absorption and emission wavelengths computed for such model solution-phase structures agree with the experimental data in a reasonably satisfactory manner, although an overall blue-shift was observed, and the excitations analysis showed a resorcynyl-thiadiazole-ligand-centered π–π* origin of the dominant electronic transitions with no involvement of the metal orbitals. The experimentally observed appearance of the low-energy absorption intensity and the red-shift of the emission signal for the complex compared to the ligand correlates well with a decrease in the HOMO/LUMO gap occurring upon the complexation. Finally, compared to NTBD, NTBD-Zn demonstrates enhanced biological activity against Gram-positive bacteria, including staphylococci, micrococci, and bacilli, while showing no effect against Gram-negative strains.