A seaweed-templated pathway was developed for the controllable synthesis of SnO2/carbon aerogel for the simultaneous removal of Hg0 and H2S in natural gases, where the SnO2 nanoparticles with an outer diameter of 4–20 nm were highly dispersed and conjoined by graphitic carbon, forming a 3D core-shell structure with a developed pore network. The synthesized sorbent performed a complete removal of Hg0 and H2S at a high space velocity of 70,000 h−1 and showed resistance to water. At 5% breakthrough, the Hg0 and H2S capture capacities reached as high as 10.37 mg g−1 and 392.23 mg g−1, respectively, which are much higher than those of the existing commercial sorbents. More importantly, the spent sorbent could be easily regenerated without significant performance degradation over five cycles. The 3D interconnected macro- and mesopores are beneficial for the Hg0 and H2S removal at a high space velocity, and the core-shell structure is conducive to prevent poisoning from water. The Hg0 and H2S removal over the SnO2/aerogel conforms to the E-R mechanism, where H2S is first adsorbed and dissociated on the SnO2 surface to produce active sulfur species, and the adsorbed sulfur then reacts with gaseous Hg0 to form HgS.