Present work focused on the flexural and thermo-mechanical characteristics of epoxy based composites filled with 3 different calcium carbonate (CaCO3) concentrations: 1.5, 3 and 5 wt.%. Composite specimens were fabricated through conventional casting method and subjected to flexural test via 3 point bending fixture. Additionally, dynamic-mechanical analyzer (DMA) with single cantilever mode was used to reval the thermo-mechanical responses of samples. The findings showed that the filler concentration increase led to the increase of storage modulus (E') for all specimens while the glass transition temperature (Tg) slightly decreased for 1.5 wt. % CaCO3 filled epoxy composite. The 5 wt.% CaCO3 loaded composite showed maximum E' and Tg values with 10% and 1.5% improvement, respectively. Based on flexural test results it was surprisingly found that, 1.5% wt. CaCO3 addition attained the highest strength with almost 27% improvement among all samples. However, 5 wt.% CaCO3 introduced composites displayed the lowest mechanical performance due to the presence of agglomerates/tactoids, which was verified from SEM images as well.