President Tony Tan has dissolved Singapore's parliament at the request of Prime Minister Lee Hsien Loong.
Lee is seeking a fresh mandate from voters worried over immigration and the high cost of living in a slowing economy.
The People's Action Party, which has ruled for more than 50 years with a mix of strict political controls and rapid economic progress, is widely expected to keep its overwhelming majority in the 89-seat parliament because of a fragmented opposition.
It will be Singapore's first election without the prime minister's influential father, independence leader Lee Kuan Yew, who died in March.
By law a general election must be held within three months of parliament's dissolution by the country's president. The date for nomination day, when candidates file their papers, is to be announced separately.
The prime minister, who had until January 2017 to hold an election, sought support in a televised address on Sunday (local time).
"This election will be critical. You will be deciding who's governing Singapore for the next five years, but much more than that ... you will be setting the direction for Singapore for the next 50 years, you will be determining the future for Singapore," he said.
Singapore celebrated 50 years of independence on August 9 with a huge parade that highlighted its rapid economic development and stability under PAP rule.