We herein report a rigid nested metal–organic framework (MOF) featuring a unique thermoresponsive gating adsorption behavior, which, in contrast to any known flexibility modes for stimuli‐responsive MOFs, depends on the thermal motion of the extra‐framework counterions. In addition, this MOF also exhibits adsorption selectivity of CO2 over N2, H2, and Ar at 273 K, thus enabling a strategic separation and encapsulation of CO2. A thermal cork screw: Counterions act as removable corks blocking the pore openings of a rigid nested metal–organic framework (MOF). The thermoresponsive gating adsorption behavior of the MOF is dominated by the counterion corks, rather than the flexibility modes of other stimuli‐responsive MOFs. On heating, the corks are removed from the openings, on cooling they return.