One of the most critical issues in designing Wireless Sensor Network (WSN) is to minimize the energy consumption. In Wireless Sensor Networks, data aggregation reduces the redundancy among sensed data and optimal sensor routing algorithm provides strategy for data gathering with minimum energy. The energy consumption is reduced by combining data fusion and cluster based routing. In this paper, we propose a K-means Fusion Steiner Tree (KFST) for energy efficient data gathering in sensor networks, which optimizes data transmission cost and the data fusion cost. This cost reduction increases the lifetime of a Sensor Network. The result of the proposed protocol KFST is compared with Adaptive Fusion Steiner Tree (AFST) and KFST produces better result than the existing protocols
