The peninsular river Damodar is the life line of eastern India, facing critical pollution problems due to sewage, industrial waste disposal as well as coal mining along the river valley. Sediment samples were collected and analyzed for various geochemical phases of hazardous elements, and associated environmental risks were evaluated. This paper provides chemical fractionation of nine (Cd, Mn, Zn, Ni, Cu, Pb, Co, Cr, Fe) elements from river sediment by using Tessier five step sequential extraction method. The study was aimed (1) to understand dynamics and mobility of elements in different geochemical fractions; (2) to evaluate bioavailability and ecological risk of these elements by RAC; and (3) to identify contaminated and uncontaminated sites by using cluster analysis. The result of the study revealed maximum bioavailable fraction was that of Cd. Bioavailable elements in studied sediment followed the order Cd (23.76%) > Mn (14.19%) > Zn (13.54%) > Ni (12.82%) > Cu (7.12%) > Pb (7.05%) > Co (6.09%) > Fe (4.98%) > Cr (2.03%). Maximum % of the reducible fraction was found for Fe (14.38%) while in organic fraction Cu (11.25%) was maximum. Residual fraction dominates in all elements with a maximum percentage of 83.85% for Co. Risk assessment by RAC reveals that the river was under medium risk due to Cd, Mn, Zn and Ni while at low risk for rest of the elements. Cluster analysis shows that three sampling sites were highly contaminated, three were moderately contaminated and six were contaminated while only one site was uncontaminated.