<p>Dry reforming of methane is a well-studied reaction for syngas production from CO₂ and CH₄. While the reaction is normally performed at a feed ratio of one, the envisioned future feedstocks contain far more CO₂ and thus require extensive separation to use the desired CH₄. Here we develop a three-step tandem electro-thermocatalytic CH₄ reforming reaction for converting CO₂-rich natural gas. The combination of the tandem CH₄ reforming process with the reverse water–gas shift reaction and an oxygen-ion-conducting electrolysis-membrane reactor, in which water electrolysis shifts the equilibrium of the reverse water–gas shift reaction, promotes syngas production and increases the apparent CH₄ reducibility. The catalyst, formed from the in situ exsolution of Rh nanoparticles on a CeO_2–<i>x</i> support, provides substantial Ce³⁺–V_O–Rh^<i>δ</i>+ interfacial active sites for high catalytic performances. This tandem system used up to four CO₂ molecules per CH₄ molecule, afforded high CH₄ and CO₂ conversions and yielded high selectivity for CO and H₂ production.</p><p></p>