A collocated finite volume method based simulation is performed to analyze the heat transfer enhancement in two-sided lid-driven cavities with the heat source embedded in the left side wall using –water nanofluid. Four cases were considered depending on the direction of the movement of the walls. The relevant parameters in the present study are Richardson number (), nanoparticles volume fraction (), the heat source length (, 0.4, 0.6, 0.8), and Reynolds number (). Comparisons with previously published work on the bases of special cases are performed and found to be in an excellent agreement. It is found that the fluid flow and heat transfer characteristics depend strongly on the direction of the horizontal walls movement. Also, significant heat transfer enhancement can be obtained due to the presence of nanoparticles.