Presidential elections were held in São Tomé and Príncipe on 18 July 2021. As no presidential candidate received a majority of the vote, a second round was originally scheduled to be held on 8 August 2021. However, following an objection to the first-round result, the second round was postponed to 29 August 2021, and later postponed again to 5 September 2021.

Guilherme Posser da Costa is a São Toméan who served as the ninth prime minister of São Tomé and Príncipe from 1999 to 2001.