Presidential elections were scheduled to be held in Singapore on 17 August 2005. 21 application forms for the Certificate of Eligibility required to contest were collected, and forms were submitted by four candidates. After considering the candidate's applications, the Presidential Elections Committee issued only one Certificate of Eligibility to the incumbent, Sellapan Ramanathan.

Sellapan Ramanathan, often known as S. R. Nathan, was a Singaporean politician and civil servant who served as the sixth president of Singapore between 1999 and 2011. Nathan won both the 1999 presidential election and the 2005 presidential election thanks to an uncontested walkover due to ineligible candidates. He was the longest-serving president in Singapore's history and the only to serve two full terms.