Humans are constantly exposed to radiations emitted by terrestrial and extraterrestrial sources, as well as radiations produced within their bodies. An attempt was made in this study to detect ambient gamma radiation levels in the Yagachi river basin, Karnataka State. Ambient gamma radiation levels were monitored in 2022 with a portable radiation dosimeter (MICRO-R-SURVEY METRE NUCLEONIX UR705) at various sites both indoor and outdoor of the study region.  The study area indoor absorbed dose rate varied from 52.2 to 243.6 nGy h^-1, with a mean of 113.1 nGy h^-1. The research area outdoor absorbed dose rate varied from 43.5 to 139.2 nGy h^-1, with a mean value of 68.771 nGy h^-1. Indoor annual effective dose range from 0.256 to 1.195 mSv y^-1, with a average value of 0.555 mSv y^-1. Outdoor annual effective dose range from 0.061 to 0.195 mSv y^-1, with a average value of 0.096 mSv y^-1.  In this study area, the absorbed dose rate and annual effective dosage were lower than the global average limit 2.4 mSv y^-1