<p>Achieving high-performance optoelectronics and sustainable water treatment is hindered by the lack of cost-effective, defect-free crystals. To balance crystalline quality with environmental impact, this study demonstrates the slow evaporation growth of high-quality (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals at room temperature, tailored for superior water treatment and optoelectronic efficiency. The solution method was used to create sodium borate–carboxylate coordination complex single crystal after a 32-day growth period. The generated (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals are analyzed by using single-crystal XRD, powder XRD, UV–Visible spectroscopy study (UV–Visible), Fourier transform infrared spectroscopy (FTIR) study, field emission scanning electron microscopy study (FESEM), energy-dispersive X-ray spectroscopy study (EDS), thermogravimetric/differential thermal analysis study (TG/DTA), photoluminescence (PL) study, photocatalytic study, Z-scan analysis study, and impedance test. The generated (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals are creating an tetragonal structure according to single-crystal XRD. It is proved by using Bruker D8 QUEST diffractometer, SHELXT 2018/2 and SHELXL-2019/2 Software. The bandgap energy value is 3.5&#xa0;eV, 65.9% transmittance, and absorbance values of (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals are measured using UV–Visible analysis. The crystalline nature and hkl values are determined through PXRD analysis. The chemical constituents and functional groups of (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals are investigated using FTIR analysis study. The surface morphology of (C₁₃B₄Na₃O₄) borate–carboxylate coordination complex single crystals is examined at high magnification using FESEM study. An EDS spectrum is used to analyze sodium, carbon, oxygen, and boron in sodium borate–carboxylate coordination complex single crystals. The (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystal’s thermal stability was measured by using TG/DTA. The emission spectra of (C₁₃B₄Na₃O₄) borate–carboxylate coordination complex single crystals is examined via photoluminescence spectroscopy analysis. The crystal is emitted the blue and green spectrum. This material also evaluates the usefulness of (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals in the industrial sectors, including textile and waste water treatment through photocatalytic study. The Z-scan analysis is used to find the third-order NLO parameters such as nonlinear refractive index (<i>n</i>₂), nonlinear absorption coefficient (<i>β</i>), and third-order nonlinear optical susceptibility (<i>χ</i>⁽³⁾) in (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals. Nonlinear refractive index (<i>n</i>₂) value is 4.6265 10⁻¹² m²/W; it indicates the positive refractive index and self-focusing behavior. Nonlinear absorption coefficient (<i>β</i>) and third-order nonlinear optical susceptibility (<i>χ</i>⁽³⁾) values are 1.287 × 10⁻⁴&#xa0;m/W and 7.50677 × 10⁻⁸ esu, respectively. The grain boundary, bulk resistance, and conductivity values are determined by using impedance technique. The values of bulk resistance (<i>R</i>_<i>b</i>) and grain boundary resistance (<i>G</i>_<i>b</i>) are found to be 155.28 and 96.11 Ω, respectively. To the best of our knowledge, this is the first report presenting the multifunctional properties of (C₁₃B₄Na₃O₄) sodium borate–carboxylate coordination complex single crystals for potential industrial and photonic applications.</p>