Catalytic combustion gas sensors are critical for safety and environmental monitoring, yet face persistent challenges in sensitivity and detection limits amid expanding market demands. This study innovatively employs attapulgite as a support material functionalized with noble metal catalyst Pd to fabricate a low-cost, high-sensitivity sensor. Characterization (SEM/EDS) confirms a unique Pd/attapulgite core–shell structure with engineered Pd gradient distribution (7.5–75.8 wt% from core to surface). The sensor achieves methane catalytic combustion below 300 °C, delivering 0.7 µV/ppm sensitivity and ~36 ppm detection limit. Reaction kinetics follow the Eley–Rideal mechanism, with voltage difference ($\mathsf{\Delta }\mathrm{U}$) versus methane concentration (C) conforming to the Langmuir equation ($\mathsf{\Delta }\mathrm{U}={\displaystyle \frac{{\mathrm{U}}_{\mathrm{m}\mathrm{a}\mathrm{x}}\cdot \mathrm{K}\cdot \mathrm{C}}{1+\mathrm{K}\cdot \mathrm{C}}}$, R² > 0.99, ${\mathrm{U}}_{\mathrm{m}\mathrm{a}\mathrm{x}}$ = 41.80 mV). Cost-effective fabrication and exceptional performance underscore its potential for practical deployment in industrial, residential, and environmental safety monitoring.