This study aims to analyze the concentrations of heavy metals and a metalloid in the surface sediments of Keenjhar Lake, Sindh, Pakistan that pose a risk to the lake ecosystem. The concentrations and ecological risks associated with eight metals and a metalloid (As, Pb, Cd, Cu, Mn, Fe, Ni, Hg, and Cr) from surface sediments of the lake, was evaluated at 10 sampling locations. The overall 95^th percentile concentrations of trace elements were observed as As (29.1), Pb (7.6), Cd (0.68), Cu (9.3), Mn (56.43), Fe (352.3), Ni (10.36), and Cr (29.61) mg/kg. Metal wise as well as aggregated levels of contamination were studied. It was observed that all metals except Hg were detected in the lake sediment. Based on the geo-accumulation index and enrichment factor, Cr, Cu, Mn, Ni, and Pb showed low pollution levels, while As, Cd, and Fe showed a high degree of contamination. Based on the 95^th percentile, the average values of EF for As, Cd and Fe were observed as 274%, 300% and 907% respectively. Pollution Load Index reflected metals and metalloid contamination near the warning threshold, with an average value of 0.825. The Nemerow integrated pollution index (range 6.79-7.59, i.e., >3) and degree of contamination (range 12-24) suggested strong pollution levels. According to the findings of the ecological risk index, Cd showed high ecological risk (between 160-320) at all sampling sites, and potential ecological risk index was at moderate risk level (between 150-300) at all locations. Multivariate analysis of the metals and a metalloid classified as As, Cd, and Fe in one group with the remaining metals in another group show that metals of each group originate from the same source.