Breaking the gas–water interfacial equilibrium of water-sealed residual gas is critical for improving recovery in water-invaded gas reservoirs. Given the limitations of existing energy-enhancement and displacement technologies, low-frequency pulsating waves can effectively disrupt this mechanical equilibrium through energy superposition and inertial interfacial effects, thus offering an innovative approach for the efficient mobilization of water-sealed residual gas. To elucidate the pore-scale mechanisms by which low-frequency pulsation mobilizes water-sealed residual gas, a customized micro-visualization apparatus was used in combination with pixel-based analysis. This approach enabled high-resolution tracking of the dynamic evolution of the gas–water interface under pulsating conditions, thereby revealing the efficacy and governing mechanisms of pulsation-driven recovery for various residual gas types. Experimental results demonstrate that low-frequency pulsating waves effectively disrupt the gas–water interfacial equilibrium, mobilizing water-sealed residual gas. Under optimal conditions (frequency: 0.1 Hz, amplitude: 12.7 kPa), an overall recovery ratio of 41.98% was achieved, with the recovery ratios for edge band gas and water-blocked gas reaching 69.59% and 35.79%, respectively. Mechanistic analysis indicates that pulsation frequency governs the superposition effect of inertial vibrations at the gas–water interface by modulating the energy supply timing. An optimal frequency range allows subsequent pressure disturbances to intervene prior to the completion of interfacial deformation recovery, inducing net displacement or fragmentation of the isolated gas clusters. Cumulative effects over multiple cycles thereby lead to a marked increase in ultimate recovery. In contrast, pulsation amplitude primarily determines the energy input per cycle, directly controlling the instantaneous degree of interfacial deformation. A higher amplitude is preferable, as it substantially increases deformation within a single cycle, destabilizes the gas–water interface more effectively, and thus elevates the per-cycle recovery efficiency. These findings provide a scientific basis for optimizing process parameters in low-frequency pulsation techniques aimed at enhancing the mobilization of water-sealed residual gas resources.