In this work, tin sulfide nanosheets decorated on face-mask-derived activated carbon have been explored as electrode material for electrochemical supercapacitors. A hydrothermal route was employed to grow tin sulfide on the surface and inside of high-surface-area face-mask-derived activated carbon, activated at 850 °C, to produce a hierarchical interconnected porous composite (ACFM-850/TS) structure. The presence of tin sulfide in the porous carbon framework exposed the surface active sites for rapid adsorption/desorption of electrolyte ions and ensured high utilization of the porous carbon surface. Furthermore, the porous ACFM-850 framework prevented the stacking/agglomeration of tin sulfide sheets, thereby enhancing the charge-transport kinetics in the composite electrodes. Benefiting from the synergistic effect of tin sulfide and ACFM-850, the resulting ACFM-850/TS composite exhibited an attractive specific capacitance of 423 F g at a 0.5 A g current density and superior rate capability (71.3% at a 30 A g current density) in a 1.0 M NaSO electrolyte. In addition, we fabricated a planar symmetric interdigitated supercapacitor on a stretchable Spandex fabric using an ACFM-850/TS composite electrode and carboxymethyl cellulose/NaClO as a solid-state gel electrolyte employing a scalable screen-printing process. The as-prepared stretchable supercapacitors displayed an ultrahigh energy density of 9.2 μWh cm at a power density of 0.13 mW cm. In addition, they exhibited an excellent cyclic stability of 64% even after 10,000 charge-discharge cycles and 42% after 1000 continuous stretch (at 25% stretching)/release cycles. Such screen-printed interdigitated planar supercapacitors with activated carbon composite electrodes and a solid-state gel electrolyte act as promising low-cost energy-storage devices for wearable and flexible integrated electronic devices.