As resource-constrained network technology develops, such as wireless sensor networks, connectivity to an IP-based network has become an important requirement. Assigning the global unique address to network nodes is a prerequisite to the connectivity to the IP-based networks. Since conventional address autoconfiguration protocols require high network bandwidth and management cost, they are not suitable for wireless sensor networks. In this paper, we propose a lightweight address autoconfiguration mechanism for resource-constrained networks. The proposed algorithm uses three coordinators that assign geometric information to the network to remove the assumption that each node has location information. Each node gathers the hop distance from the coordinators and generates a unique address based on the location information. The proposed algorithm is implemented with real hardware, and the performance is evaluated. The result shows that the mechanism efficiently assigns unique addresses to sensor nodes.