Wireless sensor network (WSN) employs the mobile sink to collect the information from the sensor nodes that are deployed in the network environment in such a way to reduce the energy hole issues. However, the placement of mobile sinks optimally in the network without degrading network lifetime result in a great challenge. Thus, the adjacency-based cell score factor is adopted in this research in order to place the mobile sink optimally in WSN. Here, the network is transformed into the cell using the Voronoi transformation. For each uniform-sized cell, the cluster head (CH) is selected using Sparse-Fuzzy C-means clustering. The optimal placement of the mobile sink is carried out using the adjacency-based cell score, which effectively places the mobile sink using the constrained factors, such as energy, Euclidean distance, and fairness. The proposed adjacency-based cell score obtained better performance with a minimal distance of 22.4615m, maximal energy, fairness, network lifetime, and throughput of 97.2182, 92.6064, 145, and 95.8852, respectively, while considering 400 nodes.