The tourism industry is a very important economic sector for many countries in the world. Therefore, tourism sustainability is an increasingly urgent issue to be addressed. Several case studies show that the implementation of sustainable differentiation based on local wisdom has succeeded in increasing the competitive advantage of tourism destinations. However, implementing sustainable differentiation based on local wisdom in achieving competitive advantage in the tourism industry is a complicated effort, because the direction and results must meet environmental, social and economic requirements at the same time. This research aims to determine the values of local wisdom as a potential source of sustainable differentiation that is integrated into tourism development that achieves competitive advantage in the Samosir Island tourist destination. This research uses a qualitative method with a case study approach. The data used is primary data and secondary data. The research results show that there are local wisdom values that are integrated in the implementation of sustainable differentiation, but they still have impacts and challenges in their implementation. Overall, the local wisdom-based sustainable tourism development strategy is a holistic approach applied to tourism on Samosir Island, through a combination of local wisdom values with sustainability principles to develop tourism destinations.