The present study deals with estimation of effective thermal conductivity of short fibers with polymer composites. This work proves enhancing the thermal conductivity property of composites can be achieved with the addition of short fibers (glass) whose thermal conductivity is more than the matrix material. In this work short glass fibers of 3 mm in length used and added in a proportions ranging of 0%, 2%, 4%, 6% by volume fraction and polyester resin as matrix material and have been prepared by simple hand Lay-up technique. The apparatus is used to find thermal conductivity is Lee’s Disc apparatus. And to validate the apparatus, experiment has been carried out to determine the thermal conductivity of existing material (glass) whose thermal conductivity is known. Thus experimentally determined values of the composite are then compared with the analytical models such as Rule of mixture (ROM), Maxwell model and Bruggeman model. Further finite element analysis (FEA) is used to determine effective thermal conductivity of the composite materials using commercially available software ABAQUS. From the obtained experimental results, numerical results and FEA results, it can be observed that there is a gradual increase in effective thermal conductivity of the composites with the addition of glass fiber content. This study also proves that FEA is a best method to validate and to compare with experimental results of the investigation. And with this unique increased thermal conductivity property and light weight composites can be used in many sophisticated applications.