Micro cellular polymer foams find numerous applications such as in filtration, tissue scaffolds, insulation, and catalyst carriers. This study reports on a solvent free approach to fabricate microcellular poly lactic acid foams through a combination of additive manufacturing and microwave foaming. This approach provides the capability to foam polymers in a repeatable and controllable manner with minimal human intervention. Initially, samples are 3D printed, followed by gas saturation, and microwave foaming. The effect of microwave foaming parameters, namely power, temperature and time on the pore morphology was analyzed using a complete parametric study. The results show that microwave foaming can successfully generate porous structure with power and temperature being the main factors affecting the pore morphology. A combination of midrange power and high temperature results in foams with desired properties of small pore size and high porosity. The resulting foams have pore size as small as 120 μm with porosity of 78%. These foams fabricated using a solvent free approach find applications in biomedical field as three dimensional tissue scaffolds for drug testing and bio‐artificial organ development.