The prolonged existence of wireless sensor networks (WSNs) is a major issue that impacts the application of such networks. This issue can be addressed by sink mobility which is an effective way to enhance network lifetime. Most of the proposals give evidence of lifetime improvement, however, joint optimization of sink mobility and routing is still an important area in WSNs. In this paper, we present need-based clustering (NbC) with dynamic joint sink mobility (JSM) scheme (DYN-NbC-JSM) for WSNs. Our proposed scheme increases the stability period, network lifetime, and throughput of the WSN. The scheme incorporates dynamic sink mobility in a way that two mobile sinks jointly move in the regions of highest density and sparsity. Intelligently moving the sink to high density region ensures maximum collection of data. As, more number of nodes are able to send data directly to sink, therefore, significant amount of energy is saved in each particular round. Secondly, moving another sink to sparse region, save the energy for nodes which due to communicating at long distances (as sparsely disributed) are close to death. However, there is certain limitation to this approach. Nodes which are far from sink have to wait much for their turn. So, there is chance of buffer overflow that is not desirable. To overcome this issue our scheme includes NbC. Clustering (communication via CHs) becomes the part for those regions which are away from both sinks. Simulation results show that DYN-NbC-JSM outperforms the other two protocols DYN-NbC-SSM (single sink mobility scenario) and M-LEACH in terms of stability period, network lifetime, and network throughput. © 2015 IEEE.