The objective of this study was to investigate the potential use of cassava steep liquor (CSL) alone and in combination with potassium phosphate and ammonium sulphate (inorganic nutrients) as biostimulation-bioaugmentation agent in the bioremediation of crude oil contaminated waters. Bioremediation was carried out for six weeks at ambient temperature in plastic bucket bioreactors containing water artificially contaminated with 10% (v/v) Bonny light crude oil. CSL alone and in combination with potassium phosphate and/or ammonium sulphate was added to each bioreactor. Similar contaminated water without CSL and potassium phosphate/ammonium addition served as control designated as natural bioattenuation. The results revealed that natural bioattenuation, CSL supplementation, CSL + potassium phosphate, CSL + ammonium sulphate, and combined CSL + potassium + ammonium sulphate remediation systems elicited 40%, 58.5%, 67.7%, 64.1% and 77.4% total petroleum hydrocarbon degradation and a corresponding biochemical oxygen demand (BOD) reduction of 52%, 62.7%, 71%, 66.7% and 81.7%, respectively. The microbial load in the contaminated water increased rapidly between days 0 and 7 and decreased between days 14 and 42 in all the remediation systems. A first-order kinetic model fitted well to the biodegradation data and the corresponding half-life time was also estimated. The model revealed that crude oil contaminated water under combined CSL + potassium + ammonium sulphate treatment strategy had higher biodegradation rate constants, as well as lower half-life times, than other remediation systems. Thus, the results suggest that CSL and in combination with inorganic nutrient could be an indispensable tool in bioremediation of petroleum hydrocarbons contaminated environment.