With the geometric population growth in developing nations comes increase in waste generation, these wastes ranging from industrial to agricultural to municipal solid waste calls for measure for its effective management and disposal so as to preserve the ecosystem. An effective measure of containing this large waste generated, is through the use of landfills which are designed and built to protect infiltration of leachates from decomposed waste to the groundwater. It is with this in mind, that this study seeks to assess the effect of bentonite (0 to 15%) on clayey soil as a base liner for landfills. In achieving this aim, two clayey samples gotten from a borrow site at a depth of 1.5 and 2.0m for samples A and B respectively were modified with bentonite. Particle size analysis, moisture-density relationship and permeability tests were performed on the test and the bentonite-modified samples in accordance with relevant standards. Result shows an increasing plasticity index, and liquid limit of both samples with increasing bentonite content. Permeability and dry densities of the samples decreases on bentonite modification. The application of bentonite modified the soil as it improves their plasticity and hydraulic properties. Bentonite modification made the clayey soil suitable for use as a liner material in landfills for municipal solid waste containment.