The concentrations of some heavy metals in Osun river at three different locations in Osun State, Nigeria were determined using physicochemical parameters and inductively coupled plasma optical emission spectroscopy techniques (ICP-OES). Three points (a, b, c) were located along the river and samples were collected in triplicates, before the rainy season (1), during the rainy season (2), and after the rainy season (3). The results revealed that the physicochemical parameters were within permissible limits except BOD and conductivity which were higher in some locations and seasons. Varying levels of essential nutrients such as Na, Mg, Ca and K were detected with the highest concentrations found to be Na followed by Ca and Mg. Toxic elements such as Cd, Fe, Cr, Mn, Ni, Al, and Pb were above the permissible limits across all points and seasons with Cd being the highest. This shows that the river is polluted and the potential sources of the metals may be due to sewage discharge, human waste discharge, landfill run off and precipitation-induced leaching. Citizens and tourists should be educated on the dangers of drinking the river water due to the associated health risks of the present heavy metals such as cardiovascular diseases, carcinogenic effects, and neurological disorders and further studies should be carried out on the river from time to time to monitor the pollution.