In the present work, fluid flow and heat transfer characteristics of Al2O3-water nanofluid in a two-sided lid-driven cavity with wavy walls is investigated numerically. The top and bottom flat walls of the cavity are driven in opposite directions, while the vertical wavy walls are maintained at different temperatures. The influence of the geometric parameters such as the amplitude of a wave and the number of undulations together with the Richardson number and volume fraction of the nanofluid in fluid flow and heat transfer is studied. The results demonstrated that both flow and temperature distributions are sensitive to the geometric parameters. It is also shown that introducing nanoparticles to the base fluid enhances heat transfer considerably for all Richardson numbers considered in this study.