Recently, the routing protocol for low power and lossy networks (RPL) was standardized and is considered as the default standard for routing over the low power and lossy networks. However, it has not been optimized to work effectively, especially under mobility, and suffers from frequent disconnections that result in packet loss and increased energy consumption. In this paper, an enhanced mobility routing protocol for wireless sensor network (EM-RPL) that incorporates modules to support the mobility of nodes has been proposed. The main goal of the EM-RPL is to increase network reliability and efficiency by selecting a route that is more stable and reduces the frequency of route discovery process. The performance of the proposed EM-RPL has been evaluated in the Contiki-based Cooja simulator and compared with the performance of other protocols that support mobility in the RPL. The simulation results demonstrated that the EM-RPL improves the packet delivery ratio and minimizes power consumption by allowing the mobile nodes to select a more stable path.