Advancement in wireless technology has promoted the emergence of the Internet of Things (IoT). Specifically, radio-frequency energy harvesting can accelerate the development of IoT technology by enabling the use of miniaturized batteryless sensor nodes. To ensure efficient energy harvesting, the impedance of the antenna and the rectifier should be matched through an impedance matching network. We present RectBoost, which is a dynamically adaptive matching network, for optimum harvesting performance of rectenna. RectBoost monitors the output voltage of the rectifier and accordingly tunes the impedance matching mode. This technique helps the rectenna overcome early state impedance mismatch by dynamically tuning matching networks. RectBoost provides two main advantages over prior works - output voltage and charging speed boost. Simulation results show that the output voltage is increased by 7 times, and the charging speed is improved by 48 times compared with those of the methods mentioned in prior works.