Dr. Nishikawa went into service for the Japanese government in 1982. In 1988, he was appointed a visiting research scholar at MIT. In 1992, he became a senior disaster relief coordination officer for the UN Department of Humanitarian Affairs, where he coordinated international assistance to numerous disaster-stricken countries.

In 2001, he became the executive director of the Asian Disaster Reduction Center. Three years later, he resumed government service to hold senior positions in the Cabinet Office and Ministry of Land, Infrastructure, Transport and Tourism. In the wake of the Indian Ocean Tsunami in December 2004, Dr. Nishikawa coordinated the Japanese government's technical assistance to affected countries. He hosted and coordinated the 2005 UN World Conference on Disaster Reduction, where the Hyogo Framework for Action was adopted. He also proposed the Japanese BCP guideline in 2005.

After the Great East-Japan Earthquake in March 2011, he initiated long-term regional recovery planning for Tohoku. Presently, he serves as director general of audits at the Japan Water Agency. He is an academic board member of the Institute of Social Safety Science. Previously, he was chair of the World Economic Forum Global Agenda Council on Catastrophic Risk.