Capturing carbon dioxide using porous materials such as zeolite and metal–organic frameworks (MOFs) could be one of the best efforts to reduce greenhouse gas emissions. This study was aimed at investigating the effect of the addition of Indonesian activated natural zeolite (ANZ) into MOF-type Materials of Institute Lavoisier (MIL-100(Fe)) on their properties and CO2 adsorption capacity. Natural zeolite was activated by acidification, which was followed by the ion exchange process. The ANZ@MIL-100(Fe) composite was synthesized by the ex situ method using sonication, with the addition of ANZ in several variations of weight for 1 h. The measurement of CO2 adsorption capacity was done by the volumetric method. The X-ray diffraction analysis showed the characteristic peaks of both ANZ and MIL-100(Fe) in the composite materials. The Fourier-transform infrared analysis exhibited absorption peaks at 1634, 1058, and 1432 cm−1 corresponding to the C=O bond from MIL-100(Fe), N–H bending, and Si–O bond of ANZ, respectively. The addition of ANZ into MIL-100(Fe) decreased the porosity, surface area, and nitrogen sorption isotherm capacity of MIL-100(Fe); however, it increased the thermal stability of MIL-100(Fe). The scanning electron microscopy–energy-dispersive X-ray analysis revealed the existence of Si and Al elements in ANZ@MIL-100(Fe). The measurement of CO2 adsorption capacity showed 300% enhancement after the addition of ANZ 20 wt% reaching up to 7.01 mmol/g.