Analysts said Sunday's vote, which featured a series of flag-waving nationwide festivities, represented a major victory for the incumbent party of President Oscar Arias, the centrist National Liberation Party, or PLN, the Tico Times reported.
The newspaper said Chinchilla, 50, had won nearly 47 percent of the vote with nearly 70 percent of the totals counted, contradicting a Unimer survey published last week in the daily newspaper La Nacion in which she had sank to 41.9 percent.
The Tico Times said Chinchilla scored victories in all of Costa Rica's seven provinces -- the first time in 25 years that has happened.
"Wives and working women continue overcoming barriers to make a greater Costa Rica," Chinchilla said in her acceptance speech. "All the women and also the men who have accompanied us have made it possible that a daughter of this country can today be president."
The second-place candidate, Otton Solis of the Citizen's Action Party, had 23.3 percent of the vote and conceded defeat, CNN reported.