In the city centre of Isparta, located in the southwestern part of Türkiye, indoor radon concentrations and gamma dose rate levels were observed above the world and country averages. For this reason, the determination of the natural radioactivity levels in soil samples of Isparta province is of great interest. In the present study, the activity concentrations of radionuclides (namely 226Ra,232Th, 40K and 137Cs) were investigated in the soil samples collected from 72 different points including the city centre and 12 towns of Isparta by using a gamma spectrometer with a high-purity germanium (HPGe) detector. The activity concentrations of 226Ra,232Th, 40K and 137Cs radionuclides in the samples were found in the range of 4.08 ± 0.39–69.84 ± 1.43 Bqkg−1, 2.63 ± 0.28–65.66 ± 1.41 Bqkg−1, 44.48 ± 3.17–452.38 ± 9.65 Bqkg−1 and 0.28 ± 0.18–19.10 ± 0.61 Bqkg−1 respectively. The averages of all the measurements were determined as 15.69 ± 0.72 Bqkg−1 for 226Ra, 15.40 ± 0.78 Bqkg−1 for 232Th, 210.60 ± 6.22 Bqkg−1 for 40K and 3.44 ± 0.31 Bqkg−1 for 137Cs. Although these values were below the country and world averages, it was revealed that the 226Ra and 232Th activity concentrations in the city centre exceeded the national and world averages. In addition, radiological risk maps of the analysed radionuclides were produced for the first time, covering all towns within the Isparta province. To evaluate the radiological hazards resulting from natural radionuclides, external hazard index (Hex), absorbed dose rate (D), annual effective dose equivalent (AEDE), male and female lifetime cancer risk (LCR) values were also calculated. The outcomes of this study revealed that all the radiological parameter averages for Isparta were lower than the world and country averages but the calculation results for the city centre displayed the opposite of this situation except for the external hazard index.