The committee's selection of Karman, a journalist and longtime human rights activist, is a nod to the democratic revolutions that have swept North Africa and the Middle East since early in the year. Karman has organized antigovernment protests against Yemeni President Ali Abdullah Saleh and in 2005 founded Women Journalists Without Chains to demand wider freedom of expression.
Karman, 32, has inspired youth rallies for civil rights and economic opportunities in an impoverished, conservative Muslim nation. She has also often criticized religious extremists, including those in the opposition Islamic party Islah.
Karman stunned many in the country when she removed her face veil during a human rights conference in 2004.
When peaceful sit-ins started in Yemen in January, Karman was among the thousands who began camping out in a tent city near Sana University in the capital.
"This prize is recognition that the international community recognizes the Yemen revolution," Karman said Friday. "My winning of the Nobel is a victory for the martyrs and the injured of the youth revolution."
Her activism and protests have agitated Saleh's teetering government, which has refused to grant Women Journalists Without Chains a license to start a newspaper. The Ministry of Information blocked Karman from sending out SMS bulletins on human rights.
The many activists in the still-unfinished revolutions in Egypt, Libya, Yemen and other countries complicated the Nobel committee's efforts to award the prize to one person who would symbolize the effect that youths and social media have had on inspiring the uprisings.
In announcing the award, Jagland said of Karman, "Many years before the revolutions started she stood up against one of the most authoritarian and autocratic regimes in the world."
Times staff writers Fleishman and Dixon reported from Cairo and Johannesburg, South Africa, respectively. Special correspondent Zaid al-Aalayaa in Sana, Yemen, contributed to this report.