Cellulose fiber-containing thermoplastic composite materials are being used in an increasing number of applications produced typically by injection molding and extrusion processing methods. One potential way to manufacture thermoplastic cellulosic fiber composites is foam forming technology developed originally for paper manufacturing. This article compares the low-density polyethylene (LDPE) and unrefined northern bleached softwood kraft pulp (NBSKP) composite materials prepared with foam forming, extrusion, and injection molding. The results show that the foam forming enabled three times higher Charpy impact strength properties and 68% higher tensile modulus compared to injection molded 30% NBSKP fiber-containing LDPE composites without changes in composite color. Foam forming is a potential large-scale manufacturing method for thermoplastic composite sheets used, for example, in compression molding or thermoforming.