In this study, we evaluated the effects of 10 wt% spherical silica filler (SSF) addition on 24-h compressive strength, modulus of elasticity, water uptake, and immediate setting shrinkage of conventional glass-ionomer (Fuji II and Experimental) and resin-modified glass-ionomer (Fuji II LC EM) cements. The glass-ionomer cement powders were modified by being mixed with 10 wt% SSFs with an average particle diameter of 0.3 μm. The materials were mixed to consistencies similar to the flow of Fuji II mixed with a powder-liquid ratio of 2.7∶1 (w/w). The 24-h compressive strength, modulus of elasticity, water uptake, and immediate setting shrinkage were observed and the results compared with the original materials mixed with similar flow. The addition of SSF increased the compressive strength value to 1.1 times, while the increase of moduli of elasticity was 1.10 to 1.35 times. In general, the addition of SSF decreased the 24-h water uptake to 80–90% and reduced the immediate setting shrinkage to 70–79% of the original materials. The addition of 10 wt% SSF improved the characteristics of conventional and resin-modified glass-ionomer cement.