The extrusion process has numerous advantages in the production of cement materials; however, cement extruded products over gain bulk density, adding costs to their fixation, workability, and application as structural reinforcement. The objective of this research was to develop and test extruded lightweight cement-based boards with the addition of superabsorbent polymer (SAP). A plain cement board containing 70% of cement and 30% of limestone filler was prepared. The different percentages of SAP from 0.0 to 2.0% based on cement mass did not interfere in the extrusion process. However, an expansion of the cement boards containing 1.0, 1.5, and 2.0% SAP occurred when passing through the extruder nozzle. The apparent porosity increased, and millimetric voids arose in the cement boards by increasing the SAP percentage. The apparent density of the cement boards favorably decreased from 8.6 to 28.4% by adding different percentages of SAP. However, the microstructural modifications raised the water absorption and substantially decreased the mechanical performance. Still, adding only 0.5% of SAP reduced the bulk density by about 10% without substantially decreasing the mechanical performance of the cement boards. Therefore, the SAP was very efficient in producing lightweight cement boards by extrusion.