The availability and quality of groundwater for drinking purpose is steadily decreasing due to influx of contaminants and high rate of extraction. Fluoride contamination in groundwater is posing serious threat to human health, being a reason of dental and skeletal fluorosis. The present study is aimed to assess the current status of fluoride in groundwater resources of Lucknow, Uttar Pradesh, India, and geoclassify the location on the scale of fluorosis threat. The study was conducted in eight blocks of Lucknow, targeting 190 spots. 82.11% of groundwater samples were found within the permissible limit, while 17.89% samples revealed fluoride concentration higher than the permissible limit (1.5 mg/L) prescribed by WHO in 2011. It was observed that around 81.47% population of Sarojininagar, 62.51% population of Kakori, 43.03% population of Mohanlalganj, 6.16% population of Gosaiganj, and 5.47% population of Chinhat are currently exposed to high fluoride concentration (> 1.5 mg/L) and prone to risk of adverse health effect posed by excess fluoride consumption. If the current scenario continues, the proportion of population vulnerable to fluoride toxicity may increase in the future.