<p>The primary objective of this study is to investigate the optical, physical, and structural properties of cobalt-doped lithium zinc phosphate glasses with the general composition 45P₂O₅–25ZnO–(30 – <i>x</i>)Li₂O–<i>x</i>Co₃O₄. Glasses were synthesized via the conventional melt-quenching technique, successfully forming a stable glass network with cobalt oxide concentrations up to 6&#xa0;mol%. X-ray diffraction analysis confirmed the amorphous nature of the synthesized glasses. The density and molar volume were found to vary systematically with composition, reflecting structural modifications due to Co₃O₄ incorporation. Infrared (FTIR) and Raman spectroscopic analyses revealed notable structural changes upon substituting Li₂O with Co₃O₄, indicating alterations in phosphate network connectivity. UV–Visible spectroscopy exhibited absorption bands in the 400–700&#xa0;nm range, attributed to the presence of cobalt in both Co²⁺ and Co³⁺ oxidation states. Optical studies showed variation in Urbach energy with dopant concentration, along with an increase in the nonlinear refractive index as cobalt content increased. The calculated metallization criterion (M) values suggest that the prepared glasses possess semiconducting behaviour, making them promising candidates for nonlinear optical applications. Based on these findings, cobalt oxide-doped lithium zinc phosphate glasses are suitable for potential use in advanced optoelectronic applications, particularly in digital display devices.</p>