Acrylonitrile butadiene styrene/nanoclay/polymethyl methacrylate nanocomposites were chemically foamed using injection molding process under different processing conditions. X-ray diffraction, scanning electron microscopy, and standard experimental tests were employed to study the morphological and mechanical properties of nanocomposite foams. The hardness is increased by 54%, and tensile strength is improved by 10% in samples containing 2wt% of nanoclay compared to pure polymer. The effect of input parameters on the morphological and mechanical properties is studied using Taguchi approach. According to analysis of variance results, holding pressure is the most effective parameter on cell size, cell density, and relative density with the contribution of 90%, 70%, and 41%, respectively. On the other hand, nanoclay content is the most effective parameter on the tensile strength and hardness with the contribution of 79% and 89%, respectively. Analytical hierarchy process is used as a multi-criteria decision-making method in order to select the best alternative among different samples considering different morphological or mechanical criteria based on sensitivity analyses. Polymeric nanocomposite foam sample produced at 2wt% nanoclay, injection pressure of 140MPa, and holding pressure of 110MPa was the best alternative in most cases.