The poll is seen as a test of support for the People’s Action Party, which has run Singapore since independence. The party saw its share of the popular vote slip to a record low in May’s general election.
Voters expressed their anger over immigration, living costs and high government salaries.
The four candidates in the presidential election all share the same surname, Tan.
Tony Tan, a former senior government official, is widely seen as being backed by the establishment.
He faces off against three rivals, all of whom are promising to shake up the ceremonial presidency.
One of the candidates, Tan Kin Lian, is even offering to donate at least half of the salary, which he estimates at $3.5m, to charity.