“These three stood out as being particularly courageous, persistent, principled and innovative and at a very high level of risk,” said Philip Lynch, director of the International Service for Human Rights, one of 10 rights organizations on the nominating jury.

Ms. Zaitouneh, who set up the Violations Documentation Center to track deaths and abuses in Syria’s jails, went into hiding in 2012 and was abducted a year later along with her husband and two colleagues, apparently seized by an armed rebel group. She has not been seen since. The Zone 9 Bloggers covered political and constitutional issues in Ethiopia and the treatment of political detainees there. Some of them faced terrorism charges that were later dropped, although prosecutors have appealed that decision; three of the bloggers have fled the country.

Mr. Tohti, a professor at Minzu University in Beijing, was a blunt critic of China’s policies encouraging Han settlement in the Xinjiang region, in China’s far west, and he called for Uighurs there to have access to the same economic benefits as Han and to be allowed to preserve their Turkic culture. At the same time, human rights groups say, he argued against separatism and expressed concern about growing militancy among Uighurs in the region. Mr. Tohti was repeatedly placed under house arrest, and in 2013, he was prevented from leaving China to take up a post as a visiting scholar at Indiana University.

In January 2014, Mr. Tohti was arrested at his home in Beijing and sent to Xinjiang’s capital, Urumqi, where, that September, he underwent a two-day closed trial, accused of leading a separatist group and of “internationalizing” the problems in the region. His subsequent life sentence was condemned by the United States and other foreign governments and by rights groups.

“By giving him life they were sending an extreme message that there is simply no room, even through peaceful means, to criticize state policies in Xinjiang,” Sophie Richardson, the China director at Human Rights Watch, said by telephone. “We see his work as part of the solution to the situation in Xinjiang, not as part of the problem.”