This article reviews the process and the background of the Sendai Partnerships 2015–2025 proposed by the International Consortium on Landslides, from its foundation to 2005 Letter of Intent proposed in the Second United Nations World Conference on Disaster Reduction (WCDR) in Kobe, Japan, in 2005, and the 2006 Tokyo Action Plan as the first stage of development to the Sendai Partnerships. It further reviews the 10th Anniversary Conference of International Consortium on Landslides (ICL) that was held in January 2012 where the ICL Strategic Plan 2012–2021 was developed. Following the Strategic Plan, ICL-IPL Conference was organized in Kyoto, Japan, in November 2013 when the concept and the initial draft of the ICL-IPL Sendai Partnerships to be linked to Third United Nations World Conference on Disaster Risk Reduction (WCDRR) were adopted. A process to establish the Sendai Partnerships in the Third WCDRR was examined in the International Forum “Urbanization and Landslide Disaster” held in Kyoto University, in October 2014. Thereafter, consultations over and the revision of the proposed partnerships were carried out to reach the final version of the Sendai Partnerships. The final version was approved in a formal “Working Session” of the Third WCDRR, agreed, and signed by the 16 intergovernmental, international, and national organizations. Those processes and the signing ceremony as well as the Sendai Partnerships are reported in this article. ICL invites all relevant organizations and individuals to support this voluntary contribution to the Third WCDRR, Sendai, Japan.