Green synthesis of nanoparticles is more promising versus chemical and physical methods as it is environmentally friendly, cost-effective, and non-toxic. Considering environmental sustainability, this study was designed to explore Itsit (Trianthema portulacastrum) efficacy for green synthesis of nanoparticles. The main objective of this study was to investigate the potential of zinc oxide (ZnO) nanoparticles developed from Itsit extract, through green methods for the treatment of textile dyes. This investigation reports that using the plant extract of Itsit, synthesis of nanoparticles of zinc oxide occurs in which zinc oxide is used as a precursor. In the green method, the plant extract that includes the biomolecules is used to reduce the zinc ions into zinc atoms like ZnO nanoparticles. Flavonoids, phenolic compounds, terpenoids, alkaloids, and flavone are all plant metabolites, the potential reducing agents used for ZnO nanoparticle preparation. The zinc oxide nanoparticles were prepared and characterized through UV--visible, FT-IR, and Zetasizer. The application of nanoparticles developed for their photocatalytic potential was investigated for the decolorization of a synthetic dye, phenol red. The ZnO nanoparticles prepared from Itsit showed 38% decolorization of phenol red, showing its promising catalytic potential under sunlight. Based on these findings, it can be concluded that Itsit demonstrated promising photocatalytic potential for the remediation of textile dye and could be employed for the treatment of textile wastewater.