With mushrooming of wireless wearable devices, demand of efficient electromagnetic interference (EMI) shielding material gained much interest to obstruct the unwanted radiations. This paper reports the fabrication of CaCu3Ti4O12(CCTO)/CoFe2O4(CFO)/silicone composites and investigation of their dielectric and EMI shielding characteristics. The EMI shielding effectiveness and dielectric properties of prepared composites are evaluated for different compositions of CaCu3Ti4O12 (50, 35, 25, 15 wt%) and CoFe2O4 (0, 15, 25, 35 wt%) in silicone matrix. The dielectric constant found maximum (~ 50) for CCS-3 composite. The CaCu3Ti4O12/CoFe2O4/silicone composites (0 and 35% CoFe2O4) exhibited total shielding effectiveness (SET ~ 6 dB) corresponds to 75% shielding efficiency in X-band. By introducing magnetic filler with CaCu3Ti4O12 in silicone matrix, better EMI attenuation is remarkably achieved. The shielding mechanism displays synergistic contribution of magnetic particles, colossal dielectric particles, and insulating elastomeric matrix. This work provides an avenue for developing better electromagnetic radiation shielding material for wearable electronics, and dielectric resonators.