Polyurethane foam is a polymeric material having cellular structure. Multifunctional polyurethane foams reinforced with nanofiller have combined enhanced specific properties with density reduction. This article primarily considers important aspects of various foam processing techniques. Numerous nanofillers such as graphite, graphene, graphene oxide, carbon black, carbon nanotube, nanoclay, and inorganic nanoparticle have been reinforced in polyurethane foam. Particular attention is given to various categories of polymer/carbon nanofiller and polymer/inorganic nanofiller composite foams. Applications of polyurethane composite foams have been focused with relevance to aerospace and automotive industry, radar absorbing and electromagnetic interference shielding, oil absorbants, sensors, fire proof, shape memory, and biomedical materials. [GRAPHICS]