Abstract: Graphene flakes (GF) with different additions (0, 4.0%, 6.5%, 12.0%, 16.8%, 20.9%, mass fraction) were added into polyvinyl alcohol-polyacrylamide (PVA-PAAM) double-network hydrogel to prepare GF/PVA-PAAM composite double-network hydrogels. The effects of GF addition on the electromagnetic shielding and microwave absorption properties of the hydrogel were investigated. The results show that with the increase of GF addition, the electromagnetic shielding efficiency, absorption efficiency and reflection efficiency of the GF/PVA-PAAM hydrogel first increased and then decreased, the reflection loss first decreased and then increased, and the microwave absorption capacity first increased and then decreased. The electromagnetic shielding efficiency was the highest when the GF addition reached 16.8%, which was 27.29 dB. When the GF addition was 6.5%, the reflection loss of the hydrogel under 2.5 mm thickness and 9.6 GHz was the lowest, which was −23.36 dB, and the effective absorption width was approximately 2.12 GHz. Adding GF improved the electromagnetic shielding and microwave absorption properties of the double-network hydrogel as well as the tensile strength.