Fluoride (F−) is a naturally occurring ion that is released by weathering of minerals, volcanic emissions, industrial activity, inputs of phosphate fertilisers and use of high-fluoride ground waters for irrigation. While low fluoride exposure may elicit neutral or stimulatory responses at times, excess fluoride is phytotoxic and a threat to crop productivity, food quality, and agricultural sustainability. Plants take in fluoride mainly through roots from contaminated soil or irrigation water and by foliage from atmospheric deposition. It is then transported in the transpiration stream and often accumulates in leaf margins and tips. The excess F can interfere with membrane function, mineral nutrition, photosynthesis, respiration, enzyme activity, cellular redox balance and reproductive development. The major effect of fluoride stress is the generation of excess reactive oxygen species, leading to lipid peroxidation, protein damage, pigment degradation and growth inhibition. Plants have several mechanisms to counteract fluoride exposure, including antioxidant defences, accumulation of osmolytes, reduction of uptake, storage in vacuoles and export of fluoride by fluoride exporter (FEX) transport proteins. However, the extent of damage differs among crop species, cultivars, developmental stages, soil properties and fluoride sources. This review summarises the current knowledge on sources of fluoride, uptake and transport, molecular mechanisms of toxicity, physiological and biochemical responses, food-chain implications, and mitigation practices. Effective remediation must combine source control, irrigation-water management, soil amendments, tolerant cultivars, beneficial microorganisms and judiciously selected phytoremediation strategies. Future research needs to consider field scale threshold values, crop specific food safety standards, genotype-based breeding and the long-term performance of remediation measures across soil and climate conditions.