This study investigates the occurrence of elevated levels of Naturally Occurring Radioactive Materials (NORMs) in groundwater within the artisanal gold and gemstone mining areas of Southwest Nigeria by using gamma spectrometric method. Artisanal mining operations are known for their potential environmental impacts through the release of NORMs into the environment. The presence of elevated concentrations of NORMs in groundwater can pose significant risks to both human health and the ecosystem. The results show that the mean activity concentrations of NORMs in groundwater samples from the various mining sites were 220.35 ± 64. 43 Bq/L for 40K, 10.53 ± 1.80 Bq/L for 238U and 17.42 ± 3.92 Bq/L for 232Th. All these values exceed the respective limits recommended by World Health Organization (WHO) as safe values for drinking water. Monte Carlo simulations was employed to assess the extent of contamination and the associated risks due to the ingestion of NORMs through the groundwater samples. The assessment of radiological risks via deterministic and probabilistic methods shows that the groundwater of the study area portend a significant risk to the population. Based on the results, it can be concluded that the groundwater of the study area contained elevated levels of NORMs.