<p>Crystal growth has been a prominent research focussed for several years due to its significance in both environmental and technological advancements. In this study, the spectral and nonlinear optical (NLO) characteristics of glycine-doped sodium potassium tartrate (GSPT) crystals are reported for the first time. Sodium potassium tartrate (SPT), also known as Rochelle salt (NaKC₄H₄O₆·4H₂O), is recognized as one of the most essential ferroelectric materials. In this study, glycine was incorporated as a dopant to enhance and modify the crystal’s inherent properties. Single crystals of GSPT were synthesized using the aqueous solution growth technique. The structural attributes of the developed crystals were analyzed using the X-ray diffraction (XRD) method. Furthermore, linear optical properties such as absorbance, reflectance, optical transmittance, extinction coefficient, and refractive index were evaluated through UV–visible spectroscopy and the optical band gap of the sample was found to be 5.6&#xa0;eV. Additionally, the grown crystals were subjected to advanced investigations, including XRD, FTIR, EDS, and SHG analyses. The relative SHG efficiency of GSPT crystal is observed to be 1.17 times higher than that of KDP crystal and the obtained results from various studies were comprehensively discussed.</p>