Display omitted •Nano-structured TiO2 have been fabricated via green synthesis method using Trema Orientalis(L) plant extract.•First report on Heterogeneous Photodegradation of Florasulam herbicide using Green synthesized TiO2.•The optimal pH value is 7 during degradation of Florasulam.•The highest photodegradation efficiency was observed in the presence of TiO2 NPs/UV.•Photodegradation of Florasulam exhibit pseudo first order reaction and fit with Langmuir-Hinshelwood kinetic model. Florasulam is a highly hazardous water pollutant. Photocatalytic degradation process using nanoparticles are encouraging option for the destruction of pesticide. The shortcomings of the traditional photocatalytic degradation are slow reaction rates, low-utilization of visible radiation, and low immigration capacity of the photo-induced electron hole. The aim of the present study is to prepare titanium dioxide nanoparticles (TiO2 NPs) using cost effective, eco-friendly method and investigate their efficiency for the photocatalytic degradation of hazardous florasulam herbicide. The green synthesis of TiO2NPs was characterized by the powder X-ray diffraction (XRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR) analysis, Ultra-violet (UV) absorption analysis, Dynamic Light Scattering (DLS) analysis and Scanning Electron Microscopy (SEM)methods. The photocatalytic efficiency of the synthesized TiO2 NPs was investigated by removal and degradation of florasulam using a batch reactor process under the UV irradiation. Due to the small size and high dispersion of synthesized TiO2 NPs, almost complete degradation was achieved in a short period of time. The influence of different experimental parameters like effect of pH, the initial concentration of florasulam and photocatalyst TiO2 NPs dosage were investigated. The experimental kinetic data followed the pseudo-first-order model. Langmuir–Hinshelwood (L–H) kinetic model was proposed for the rate equation of the florasulam degradation in presence of TiO2 NPs under UV irradiation. Overall, the green synthesized TiO2 NPs exhibited considerable potential for fast and eco-friendly removal of harmful florasulam herbicide.