Fluoride (F−) stress is one of the major environmental pollutant, affecting plant growth, development and production, globally. Acquisition of eco-friendly F− stress reliever seems to be the major concern these days. Consequently, application of engineered nanomaterials (ENMs) has been increasing to improve agri-economy. However, the impact of silicon nanoparticles (Si NPs) on mitigation of F− stress has not been investigated yet. Thus, the present study was conducted to compare their protective roles against F− stress by improving diurnal photosynthetic efficiency of sugarcane plant leaves. An ability of sugarcane (Saccharum officinarum cv. GT44) plants to ameliorate F− toxicity assessed through soil culture medium. After an adaptive growth phase, 45 days old plants select to examine F− mitigative efficacy of silicon nanoparticles (SiNPs: 0, 100, 300 and 500 ppm) on sugarcane plants, irrigated by F− contaminated water (0, 100, 200 and 500 ppm). Our results strongly favour that SiNPs enhanced diurnally leaf photosynthetic gas exchange viz., photosynthesis (∼1.0–29%), stomatal conductance (∼3.0–90%), and transpiration rate (∼0.5–43%), significantly, as revealed by increments in photochemical chlorophyll fluorescence efficiency of PS II linked with performance index and photosynthetic pigments during F− stress. To the best of our knowledge, this is the first investigation to explore the impact of SiNPs improving and/or maintaining the diurnal photosynthetic responses in sugarcane plants in response to F− stress. It may also precisely unlayer action of molecular mechanism(s) mediated by SiNPs, found essential for mitigation of F−-toxicity to explore nano-phytoremediation approach for crop improvement and agri-economy as well. Display omitted •Silicon nanoparticles enhance diurnal photosynthetic efficiency during F− stress.•Foliar application of Si NPs alleviated negative impacts of fluoride contaminated water.•Development of analytical model to integrate physiological responses against F- stress.