Materials possessing ultrathin, lightweight and foldable characteristics while simultaneously exhibiting superb electromagnetic interference shielding effectiveness (EMI SE) are urgently required to guarantee the operation of portable electronics. Herein, a novel and facile approach is reported to controllably fabricate porous graphene films (PGFs) with chosen thickness by reduction-induced foaming of graphene oxide film with a spatial confinement strategy. In striking contrast to unconstrainedly expanded graphene films, the confined PGFs surprisingly exhibit excellent elastomeric behavior and strong repeated folding stability. Even after high and ultralow temperature treatment, the folding performance of PGFs is not compromised. Intriguingly, considerably enhanced EMI SE and microwave-absorbing phenomenon are achieved for PGFs compared to compact graphene films due to the efficient wave attenuation in the porous structure and highly conductive network. Significantly, the annealed PGFs exhibit a remarkably high EMI SE of 63.0 dB, enough to block and absorb 99.99995% of the incident radiation, which is far superior in performance compared to all graphene-based shielding materials. The largest specific SE/thickness of 49750 dB cm² g^-1 is among the highest values of all the shields known to date. Therefore, such thin, lightweight, elastic PGFs with outstanding EMI-shielding performance are highly promising for applications in foldable and wearable electronics.