Exploiting renewable energy sources is essential to ensure perpetual system operation of Internet of Things (IoT) devices. With the ever growing demands for higher level of integration and functionality, highly compact energy harvesting interfaces for efficient energy conversion are becoming indispensable. This chapter discusses high-performance integrated switched-capacitor energy harvesting interfaces for miniaturized IoT systems. In terms of the AC-type energy harvesting, we introduce the flipping capacitor rectifier (FCR) and the split-phase flipping capacitor rectifier (SPFCR) to achieve effective voltage inversion for vibration energy harvesting, obtaining a high energy extraction efficiency without using bulky high-Q off-chip inductors. For the DC-type energy harvesting, we exploit the algebraic series-parallel (ASP) topology to reduce both the intrinsic power stage conduction and parasitic losses, while enabling high-efficiency reconfigurable voltage conversion. We demonstrated all the design approaches with silicon-validated results.