In this study, influence of blowing agent residence conditions on foam attributes has been investigated in extrusion foaming process. The blowing agent injection location in the extrusion barrel was found to affect the residence time inside the barrel, which in turn significantly transformed the foam microstructure. The injection location providing higher gas residence time resulted in foams with lower cell size, higher expansion ratio, and enhanced cell density. Further studies were performed to analyze the synergistic influence of residence time variation on foam attributes at different screw rotational speeds, die temperatures, and blowing agent contents.