Increasing the lifetime of low power and lossy networks (LLN) is a major challenge, as the nodes have low power, low memory, and low processing capacity. Clustering is a technique used to minimize the energy consumption of sensor nodes. This article proposes a fuzzy sets-based cluster routing protocol (FC-RPL) to extend the network lifetime in LLN. It has three processes: cluster formation, cluster head selection, and cluster head parent selection. It forms the clusters based on the Euclidean distance. It applies the fuzzy set over the metrics residual energy, number of neighbors and centrality, to select the cluster head in each cluster. The cluster head node chooses the best parent node in the DODAG for data transfer. The simulation is performed using COOJA simulator. The simulation result shows that FC-RPL extends the network lifetime by 15-25% and increases the packet delivery ratio by 2-6%. Copyright © 2019, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited.