Summary The development of functional porous materials has attracted the attention of many researchers because of the superior properties of these materials for various potential applications, such as catalysis, adsorption and separation, water splitting, renewable energy, nanomedicine, etc. In order to improve the performance of pristine porous materials, integrating porous materials with other species to make composite materials is often necessary. As a class of such porous materials, covalent-organic frameworks (COFs) show unique and interesting properties when combining with other materials to form functional composites. In this review, we highlighted recent research advances of composite materials based on the integration of COFs with metal or metal oxide nanoparticles, metal sulfides, silica, carbon materials, polymers, metal-organic frameworks, and other COFs. In particular, we focused on the synthetic methodology and associated applications of the resultant composite materials. Some of these composite materials exhibit improved performance as compared with individual components. Thus, this review aims to facilitate further development of COF-based composite materials for desirable applications.