Abstract: Significant heat and electromagnetic radiation emitted during the operation of electronic devices drives the researches on the dual-functional materials with electromagnetic shielding and thermal management capabilities. Herein, the one-dimensional (1D) SiC whiskers and carbon nanotubes (CNTs) are combined with two-dimensional (2D) graphene to synthesize the three-dimensional (3D) dual-functional composites of graphene/CNT/SiC. A 3D porous graphene structure is fabricated using a liquid-phase reduction method via the self-assembly of graphene oxide, where CNTs are dispersed on the graphene layers and SiC whiskers are interspersed between the porous matrix. Simultaneously, a leaf-like structure is built by adhering the skeleton of CNTs and whiskers on the surface of graphene, which promotes the bonding between SiC whiskers and graphene layers by CNTs. The 3D structure of graphene/CNT/SiC improves the heterogeneous interfaces and the dual-functional characteristics are enhanced by exhibiting the thermal conductivity of 123 W·m^–1·K^–1 and shielding effectiveness of 29.3 dB with 2.0% SiC addition.