A new organic-inorganic hybrid salt, bis(2-carboxypyridin-1-ium) hexachlorostannate(IV) dihydrate ([2-CpyH]2[SnCl6]), was synthesized and structurally characterized through single-crystal x-ray diffraction, Hirshfeld surface analysis, and bond valence sum calculations. The compound exhibits a robust three-dimensional hydrogen-bonded framework and columnar packing of [SnCl6]2- octahedra, which collectively enhance structural stability and electronic polarization. Optical studies reveal a wide bandgap of 4.28 eV and strong blue-violet emission at 386 nm, indicating potential applicability in UV sensing and related photonic technologies. Z-scan measurements demonstrate a notable third-order nonlinear optical susceptibility, chi(3) = 1.75 x 10-11 esu, arising from combined reverse saturable absorption and self-defocusing behaviour, confirming the suitability of the material for optical limiting and photonic switching applications. Dielectric measurements show pronounced dispersion at low frequencies and stable, low-loss behaviour at high frequencies, supported by efficient dipolar orientation and interfacial polarization. AC conductivity analysis reveals a transition from defect-mediated conduction at low frequencies to hopping-dominated transport at higher frequencies. These combined structural, optical, and dielectric properties highlight [2-CpyH]2[SnCl6] as a promising multifunctional material for photonic, optoelectronic, and dielectric device applications.