Ex-Premier Milos Zeman and Foreign Minister Karel Schwarzenberg will compete in the second round of voting for the largely ceremonial post on Jan. 25-26.
Czechs are electing the country's president in a direct popular vote for the first time, to replace euroskeptic President Vaclav Klaus, whose second and final term ends March 7.
Since Czechoslovakia officially split into Slovakia and the Czech Republic in 1993, the republic has had two presidents elected by Parliament: Vaclav Havel and Klaus. But bickering during those votes led the legislature to give that decision to the general public.
With the votes from all of the 15,000 polling stations counted on Saturday, Zeman was leading with 24.21 percent of the vote, followed by Schwarzenberg with 23.40 percent. Another former premier, Jan Fischer, was a distant third with 16.35 percent.
Zeman and Schwarzenberg will advance to the runoff, since no candidate achieved a majority. They were among nine candidates in the race.
"It will be a presidential race between a candidate for the left and a candidate for the right," Zeman said. "We'll start from scratch for the second round."
Zeman and Fischer were considered favorites, but Schwarzenberg finished his campaign in style, attracting an unusually big crowd of about 10,000 in a rally in the capital this week.
Schwarzenberg said he would do all he can for the Czech Republic to be "a successful country."
Zeman, 68, is attempting to stage a return to power after he retired following a failure in the 2003 presidential election.
A chain smoker with a soft spot for alcohol, Zeman made international headlines as prime minister with outspoken comments. For example, he compared late Palestinian leader Yasser Arafat to Adolf Hitler, drawing condemnations from the EU and the Arab League, and called the Austrians who opposed a Czech nuclear plant "idiots."
After the Sept. 11 attacks in the U.S., Zeman and his interior minister said they believed that hijacker Mohamed Atta met with a senior Iraqi intelligence official in Prague in April 2001. That purported meeting was cited as evidence of a possible al-Qaida connection to Iraq. The 9/11 commission later said such a meeting never happened.
Schwarzenberg, 75, is chairman of the conservative TOP 09 party, a member of the center-right ruling coalition. He is a member of a European noble family, and lived in exile on his family's estates in Austria and Germany during communist rule. After the Velvet Revolution, he became chancellor to Vaclav Havel. He served as foreign minister from 2007-09 and again took the post after the 2010 general elections.
Zeman and Schwarzenberg were already looking ahead to the upcoming runoff, trading political barbs Saturday. Schwarzenberg said Zeman belongs to the past, and the ex-premier replied by saying Schwarzenberg should be held responsible for the austerity cuts pushed through by the current government that his opponent is a member.
Vladimir Franz, a renowned classical music composer and painter who has tattoos over most of his body, finished fifth with 6.84 percent. The professor at the prestigious Academy of Performing Arts in Prague with no experience in politics called it "a success."