<p><?tk 2?>In wireless sensor networks, unknown nodes are randomly deployed over the region of interest on a large scale. The accuracy of node position estimation is always desirable for location-based services. State-of-the-art systems often use one or more mobile anchors, which simplifies the localization process. However, maintaining a mobile anchor on a suitable trajectory could be very effective in speeding up the localization process. It would also reduce localization errors and energy consumption of resource-constrained nodes. In this paper, we present a new dynamic path planning strategy (DPPS) for a mobile anchor, which ensures faster and accurate localization of unknown nodes. This strategy reduces latency and extends network lifetime by localizing each node on three consecutive anchor points. At each anchor point, a unique cluster is formed with a few neighboring nodes whose received signal strength (RSS) is greater than a predefined threshold. The anchor maintains all newly encountered nodes in the current cluster toward its next two anchor points on the trajectory through variable transmission power. The proposed algorithm involves different power saving modes for the anchor and nodes to improve energy efficiency, while the use of variable transmission power ensures localization accuracy. This path planning strategy systematically eliminates the collinearity problem by ensuring a minimum area over three consecutive anchor points. Simulation results in terms of localization accuracy, energy efficiency, and trajectory length validate its competence, which is comparable to existing systems.</p>