To endow polymers with excellent electrically conductive performances, it is crucial to constructing three-dimensional conducting networks within polymer matrices. In the present work, highly porous graphene aerogels enhanced with phenolic resol resin are prepared by a hydrothermal synthesis followed by high-temperature annealing. The introduced phenolic resol resin and its pyrolysis derivative effectively combine the sheets together and thus the three-dimensional network of the enhanced aerogels is well retained even after compounding with epoxy resin. The synthesized aerogels are highly efficient in endowing epoxy with excellent electrical conductivity, electromagnetic interference (EMI) shielding efficiency and mechanical reinforcement. With only 0.33 wt% of the annealed aerogel, its epoxy nanocomposite exhibits a high electrical conductivity of 73 S/m and an excellent EMI shielding effectiveness of 35 dB. Furthermore, the aerogel significantly increases the flexural strength and flexural modulus by 67% and 20%, respectively, as compared to those of neat epoxy. Therefore, the phenolic resin-enhanced graphene aerogel holds a potential in the production of high performance polymer nanocomposites for EMI shielding. In addition, highly compressible three-dimensional graphene aerogels with anisotropic porous structure are also fabricated by directional-freezing of graphene hydrogel using anisotropically grown ice crystals as templates followed by freeze-drying. The anisotropic graphene aerogel exhibits ultralow density, excellent flexibility in liquids, satisfactory fire-resistance, and strain-sensitive electrical conductivity.