Tulviste collected 264 votes against his rival candidate Tunne Kelam's 249 at a Pro Patria Union congress held in Tallinn.
Both Tulviste and Kelam earlier reassured party colleagues that they would support the winner in the presidential elections, which will begin in August, if they were defeated.
"You can tell Estonian politics are in a healthy state when a newcomer has a greater chance of being elected than a politician who has been around for a long time," Tulviste said after the vote.
He said the Pro Patria congress made the right decision in electing him.
"I ask that our differences be left right here in this hall and we can unite, so that Pro Patria Union's principles can reach the Kadriorg," Tulviste said, referring to Estonia's name for the presidential office.
The Estonian market research company Emor carried out polls in January and April to measure the public approval ratings of potential presidential candidates. Both polls were based on 500 interviews with Estonian residents aged 15 to 74. Shown a list, they were asked which of the candidates they would like to see as Estonia's next president.
Tulviste did not figure in the January list. But according to the April opinion poll, Tulviste shot up to second place behind the Reform Party's Toomas Savi as Estonia's best presidential candidate. Savi is also parliamentary speaker.
The Reform Party has not yet decided between its candidates Savi, Mart Rask, who is the justice minister, and MP Toomas Vilosius.
Savi's rating fell from January's 31 percent approval to 27 percent in April. Tulviste polled a 21 percent rating in the survey.
Active media coverage of Tulviste as a presidential candidate and support by public opinion leaders has influenced the preferences of the public.
The drop by a couple of percentage points in Savi's approval rating cannot be regarded as particularly significant, but if Tulviste's campaign continues at its present pace a change in the people's preferences is likely.
Tulviste, born on October 28, 1945, in Tallinn, graduated from Moscow University where he got a doctor's degree in psychology in 1987. He had been on Tartu University's teaching staff since 1974, and held the post of rector of the university from 1993 to 1998.
After local elections in 1999, Tulviste became chairman of the City Council of Tartu.
The opposition Center Party and the Estonian United People's Party have officially named their presidential candidates, respectively Peeter Kreitzberg and Yevgeni Tomberg.
Another party in the ruling coalition, the Moderates, has still not announced its candidate for replacing President Lennart Meri, who was elected in both 1992 and 1996. A president cannot be elected three times.
According to Olari Koppel, the media coordinator of the Moderates, their official candidate will be revealed on May 19, at a party congress. "Before that time we'd rather not speculate on the matter," said Koppel.
According to media reports, the Moderates' likely presidential candidate is Andres Tarand, and of the People's Union Arnold Ruutel.
Matti Pats, grandson of Estonia's revered prewar president Konstantin Pats, kicked off his presidential campaign on March 29 with a tour of the southwestern region of Parnumaa. Pats has been nominated as a candidate by the Conservative Club, a non-party political organization.
Meanwhile, the post of president is becoming more attractive in terms of payment. The Parliament adopted on April 17 a law on the president's working regulations that lays down the powers of the head of state and prescribes arrangements for the fulfillment of official duties. Among these things it raises the president's salary.
Currently six times the national average, the president's monthly salary will under the new law be the average multiplied by seven - about 37,000 kroons ($2,100) - from the first quarter of 2001.