A nanopower highly efficient low-dropout (LDO) regulator for energy harvesting (EH) applications is presented in this paper. The LDO is fully autonomous with a bandgap reference (BGR) featuring a novel bandgap supply-switching (SS) topology, an over-voltage protection (OVP), a under-voltage lock-out (UVLO) and control block to obtain stable output and robust cold-start. The system provides configurable voltage supply (1.1 ~ 2 V) for potential loads, while consuming as low as 66 nW power. The entire system achieves a peak power efficiency of 95.6% at V_out = 2 V and I_load = 100 uA.