In this work, spherical Li4SiO4 pellets were produced via an extrusion-spheronization technique. This pelletization process caused the destruction of the original porous structure, a reduction of the specific surface area and, thus, a decrease in the CO2 sorption performance. Therefore, a typical pore-forming material of microcrystalline cellulose was employed to modify the inner microstructures of the pellets and thus enhanced the cyclic CO2 sorption capacity. The pellets modified with 20 wt% microcrystalline cellulose exhibited a high capacity of 0.282 g CO2/g sorbent at the 70th cycle, which is even comparable with that of the Li4SiO4 powder. It has been indicated that the performance enhancement is attributed to the increased surface area and enriched porosity. In addition, the sorbent pellets are required to possess excellent mechanical performance for the practical application in the circulating fluidized-bed reactors; therefore, the mechanical properties, i.e., compression strength and anti-attrition performance, were also tested. The results indicated that the Li4SiO4 pellets maintained quite outstanding mechanical performance. The good physicochemical properties of the pellets show that the developed Li4SiO4-based sorbents have promising prospects for high temperature CO2 capture in fluidized-bed systems.