Sharing the award were Liberian President Ellen Johnson-Sirleaf, Africa's first democratically elected female head of state; her countrywoman Leymah Gbowee, a peace activist who challenged warlords; and Tawakul Karman, a Yemeni human rights leader seeking to overthrow an autocratic regime as part of the regionwide "Arab Spring" movement.
"We cannot achieve democracy and lasting peace in the world unless women obtain the same opportunities as men to influence developments at all levels of society," said the citation read by Thorbjorn Jagland, head of the Nobel committee, based in Oslo.
The Norwegian panel said it hoped the award would help end "the suppression of women that still occurs in many countries, and to realize the great potential for democracy and peace that women can represent."
The trio joined an exclusive group of about a dozen female Nobel peace laureates among the scores of men who have won the honor over the decades.
Gbowee's associates have termed her a "warrior" for peace, and both Karman and Johnson-Sirleaf, who is facing a reelection vote Tuesday, have been nicknamed the "Iron Lady" in their countries.
There was "a lot of dancing and whooping and hollering" in Liberia's presidential office, a Johnson-Sirleaf aide said, after the 72-year-old Harvard-educated economist heard the news.
Johnson-Sirleaf said that she was humbled by the prize, but that the credit went to the people of Liberia,
"We were really happy because it was a real surprise for us," Elva Richardson, Johnson-Sirleaf's personal administrative assistant, said in a phone interview. "We are conveying to [Liberian women] that this is a celebration, a prize for all Liberian women. They're ecstatic."
The citation said that since becoming president in 2006, Johnson-Sirleaf had helped secure peace in Liberia, had promoted economic and social development and had strengthened the position of women.
But Johnson-Sirleaf's opponents reacted angrily at what they saw as interference in Liberia's domestic affairs.
Johnson-Sirleaf's main rival in the presidential election, Winston Tubman, described her as a warmonger who didn't deserve the prize. He told Agence France-Presse that its timing was provocative.
"I did more to stop the war than she did," Tubman told the BBC, referring to Liberia's 14-year civil war, which began in 1989.
Speaking to reporters in the Norwegian capital, Jagland rejected suggestions that the prize could have an effect on the election.
Johnson-Sirleaf has won previous international plaudits for her governance: The Economist said she was arguably the best president Liberia had ever had, and Newsweek named her one of the 10 best leaders in the world in 2010.
But she has faced criticism in Liberia for going back on a promise not to run for a second term, and for her initial support of Charles Taylor in 1989, when civil war broke out against the autocratic rule of Samuel Doe, who had jailed her. Once assuming power herself, Johnson-Sirleaf requested Taylor's extradition from Nigeria so that he could face trial for war crimes in Sierra Leone.
Gbowee, 39, was reportedly close to tears when she learned of the award while in New York.
"I'm numb, I'm fuzzy, I'm overwhelmed. All I keep hearing in my head is the song of praise to God," she told Reuters news agency. "My work is for survival for myself and for other women. With or without a Nobel, I will still do what I do because I am a symbol of hope in my community on the continent, in a place where there is little to be hopeful for."
Gbowee, who now works for the Accra, Ghana-based Women Peace and Security Network Africa, played a key role in ending the Liberian war by forming a group of Christian and Muslim women who held daily protests, demanding that Taylor hold serious peace talks. At one point, the women organized a "sex strike" to underscore their anger about continuing violence.