He was also chairman of the Hindu Endowments Board and was a founding member of the Singapore Indian Development Association (SINDA), and was its term trustee until August 1999.

In April 1988, Nathan was appointed Singapore’s high commissioner to Malaysia and in July 1990, he became ambassador to the United States where he served till June 1996.

After returning from the United States, Nathan became ambassador-at-large and was concurrently director of the Institute of Defence and Strategic Studies (IDSS) at the Nanyang Technological University. 

He resigned as ambassador-at-large and director of IDSS Aug 17, 1999, and was elected president of the Republic of Singapore Aug 18, 1999. He began his six-year term from Sep 1, 1999. 

He was re-elected Aug 17, 2005, and was sworn in for his second term of office Sep 1, 2005, and served in that position till Aug 31, 2011.

Nathan was conferred the Public Service Star in 1964, the Public Administration Medal (Silver) in 1967, and the Meritorious Service Medal in 1974.