The development of miniaturized and wearable electronics has triggered an urgent demand for microsupercapacitors (MSs) with high performance, reliable safety and flexibility. However, very few studies have examined the operating performance of MSs at temperatures other than room temperature due to the poor temperature tolerance of conventional polyvinyl alcohol (PVA)-based electrolytes. Herein, a novel class of high-performance flexible MSs has been developed through covering a highly conductive graphene oxide/polyacrylamide (GO-PAA) polyelectrolyte on interdigital microelectrodes of polyimide-tape-supported carbon nanotube/worm-like-structured polyaniline nanofibers patterned by laser direct writing. These polyelectrolyte-based microsupercapacitors (PMSs) show the widest temperature tolerance from −30 °C to 100 °C among all reported MSs, delivering record high areal energy densities and capacitances at −30 °C (7.48 μWh cm−2 and 84.4 mF cm−2) and 100 °C (8.55 μWh cm−2 and 96.2 mF cm−2). In comparison, PMSs possess over seven times higher specific capacitance than MSs based on current PVA/H2SO4 electrolyte at −30 °C and 100 °C. Additionally, PMSs also exhibit high safety, excellent cycling stability (94.2% capacitance retention after 8000 cycles even at −30 °C) as well as superior flexibility.