In recent years, bead foaming technology has been of great interest to researchers because it represents a breakthrough in the production of low density plastic foamed components that have a complex geometrical structure. This helps to expand the market for plastic foams by broadening their application. In this study, a lab-scale autoclave system for foamed bead manufacturing was used to produce expanded thermoplastic polyurethane (ETPU) bead foams. The foam morphology was controlled by utilizing the phase-separated hard segment crystalline domains in the thermoplastic polyurethane (TPU) microstructure as heterogeneous bubble nucleating agents. This was achieved by reprocessing the “as-received” TPU and redistributing the hard segment domains to increase the efficiency of bubble nucleation. Foamed TPU beads were obtained under various processing conditions while using carbon dioxide as the blowing agent. The cellular morphology and melting/crystallization behaviours of the beads are examined and discussed. The results shows that the evolution of microstructure caused by processing was favorable in enhancing the cell density and reducing the cell size.