Mbeki's African National Congress (ANC) is expected to easily win at the polls.
The ANC, under anti-apartheid icon Nelson Mandela, led South Africa from white rule to multi-racial democracy in 1994.
It now holds two-thirds of parliament's seats thanks to defections from the opposition, and controls all provinces except Kwazulu-Natal.
"I would like to inform the national legislature and the country that the 2004 general election... will take place on the 14th of April," said Mbeki.
Political analysts expect Mbeki to be sworn in for a second five-year term on or around 27 April, which will mark the 10th anniversary of the country's first democratic election.
Mbeki, who succeeded Mandela as president in 1999, launched the ANC's election campaign in January, vowing to fight poverty and joblessness which still plague most of the black majority.
Opposition parties, meanwhile, hope to chip away at the ANC's dominance by targeting weaknesses, including South Africa's high crime rates and a devastating AIDS epidemic that infects more than five million of the country's 45 million people.
Mbeki said electoral rolls would close at midnight (2200 GMT) on Wednesday after a registration drive which has signed up more than 20 million people, or 85% of eligible voters.
Mbeki, in his annual state of the nation address to parliament on Friday, said the ANC had outlined the basic steps necessary to resolve South Africa's problems and did not anticipate major new policy initiatives in the next 10 years.
He also urged voters to eschew the political violence which has marred earlier elections, particularly in Kwazulu-Natal where the ANC and the Zulu-dominated Inkatha Freedom Party (IFP) are already trading accusations of intimidation and attacks.
Main opposition, the Democratic
Alliance says ANC failed to deliver
The opposition has criticised Mbeki for delaying the announcement of the election date while pushing forward with the ANC's own national campaign.
The IFP, fighting hard to retain its control of the Kwazulu-Natal provincial legislature, launched its own campaign in mid-January while the country's official opposition, the Democratic Alliance (DA), started its vote drive on Saturday.
"The ANC has been put on notice. It has 10 years of broken promises and failures to deliver," DA election campaign chairman James Selfe said in a statement.