Organolead halide perovskites are used for low-operating-voltage multilevel resistive switching. Ag/CH3NH3PbI3/Pt cells exhibit electroforming-free resistive switching at an electric field of 3.25 × 103 V cm–1 for four distinguishable ON-state resistance levels. The migration of iodine interstitials and vacancies with low activation energies is responsible for the low-electric-field resistive switching via filament formation and annihilation.