In this study, the effect of adding glass ionomer (GI) Restorative Cement (0−30 wt%) on the mechanical and thermo‐mechanical characterization of dental composite has been discussed. The characterization of dental composites was done by performing Fourier transform infrared spectroscopy, hardness test, compression test, flexural strength test, dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA). The finding of experiments indicated that the addition of 10 wt% of GI increased the water hardness, flexural strength and compressive strength by 88.48, 15.95, and 17.74%, respectively. DMA results revealed that the storage modulus was initially increased by 88% when GI was increased up to 20 wt%, however, further increase of GI up to 30 wt% resulted in decrease in the storage modulus by 16.4%. Also, loss modulus was increased by 41.6% when GI was increased by 10 wt%, however, it was further decreased by 2.94% and by 35.29% on addition of GI filler content up to 20 and 30 wt%, respectively. Incorporation of GI up to 10 wt% decreased the damping factor by 36.36% but further addition of GI up to 20 and 30 wt% increased the damping factor of dental composite by 14.2 and 50%. TGA indicated that thermal degradation temperature was increased with the addition of GI filler. POLYM. COMPOS., 40:3361–3367, 2019. © 2018 Society of Plastics Engineers