Mixed matrix membranes (MMMs) create a new horizon for developing novel materials with desired separation properties, since conventional membranes are insufficient to fully accommodate in industrial applications and process intensification. A broad area of researches has been dedicated to develop MMMs for CO2 separation. MMMs are normally comprised of different kinds of fillers embedded into the polymer matrices with a final goal of surpassing the Robeson's upper boundary not only by controlling shortcomings of the available organic and inorganic membrane materials, but also through a fast upgrading of them. One of the most important aspects in the development of MMMs is an appropriate material selection for both matrix and dispersed phases to eliminate the non-ideal morphologies created at their interfaces. Development of high performance membrane materials with new functional groups and new chemistries has attracted much attention over the past few years. To have an impact on real implementations, successful MMMs are necessary to optimize multiple functions besides high porous structure and surface area, such as processability, stability, sorption kinetics, mechanical and thermal properties, while simultaneously the economic issues must be taking into account. Although, during the long years passed from applying the MMMs for CO2 separation, various kinds of conventional porous/dense materials have made significant contributions, many novel materials have rapidly emerged over the past five years. These improvements include the extensive use of a wide range of functionalized materials, which have inexorably entered the scene to substantially promote the separation performance. Today, the range of conceivable functions for porous materials is much broader than foretime. This may be indebted to the prompt progresses in design and computing the new functions/structures, which encourages the emergence of a new way to correctly identify the best material for the specific gas separation targets. Advanced functionalized MMMs generate substantial breakthroughs in tailoring successful CO2-selective membranes and recent progresses in functional materials create many attractive opportunities/perspectives. This review is especially devoted to describe the recent developments in methods proposed to preserve/overcome the afore-mentioned fabrication challenges of MMMs and also the progress in advanced functionalized materials used in the MMMs for CO2 separation during the recent years.