The March 1 carnage at a train station in Kunming, in the southwestern province of Yunnan, also saw more than 140 people wounded and was dubbed "China's 9/11" by state-run media.
Beijing blamed it on "separatists" from the resource-rich far western region of Xinjiang, where at least 200 have died in attacks and clashes between locals and security forces over the last year.
Four armed guards in helmets and dark clothing, and holding automatic weapons, were positioned inside the courtroom opposite the accused -- the three men with their heads shaved -- state broadcaster CCTV showed.
The suspects, whose names appear to identify them as members of the Uighur minority, wore prison clothes, and each had a separate dock, with two police officers sitting behind.
The woman, named as Patigul Tohti, took part in the attack along with at least four other assailants whom police shot dead at the scene, prosecutors said, and she was convicted of "participating" in the group.
State prosecutors said three of the suspects -- whose names were transliterated as Iskandar Ehet, Turgun Tohtunyaz and Hasayn Muhammad by the official news agency Xinhua -- were arrested while attempting to cross China's border, according to the court.
Militants from Xinjiang were accused of organising an explosive attack in the regional capital Urumqi which killed 31 people in May, and a suicide car crash in Beijing's Tiananmen Square last year.
The Kunming mass knifing was the biggest-ever violent incident against civilians outside the region.
Authorities had previously given the toll as 29, but the change indicated that two of the wounded had later died of their injuries.
More than 300 members of the public were present in court, Xinhua said, including some victims and their relatives.
Weibo users welcomed the death sentences. "Even if she is pregnant, life in prison is too light a sentence," one commenter wrote about Tohti. "She was able to slash so many people while carrying her own baby – scum."
- Death penalty -
China's courts have a near-100 percent conviction rate and the death penalty is regularly handed down in terrorism cases.
China last month announced the executions of eight people for "terrorist attacks", including three it described as "masterminding" the car crash in Tiananmen Square. That came after 13 people were executed in June for attacks in Xinjiang.
In a statement Thursday, China's Supreme People's Procuratorate urged prosecutors -- particularly those in Xinjiang -- to fast-track terror-related cases and "deliver exemplary penalties".
The procuratorate "emphasised that these cases must be handled without discrimination and under the principle of tempering justice with mercy", according to Xinhua.
Xinjiang, a resource-rich region which abuts Central Asia, is home to several ethnic minorities with strong cultural ties to neighbouring states such as Uzbekistan and Kazakhstan.
Uighurs, who are mostly Muslim, are its largest ethnic group but many resent decades of immigration by China's Han majority.
They say it has brought economic inequality and discrimination, as well as cultural repression such as a campaign to stop the Islamic practice of women covering their faces.
China counters that it plays a positive role and has brought about development and improvements to health and living standards.
Beijing regularly accuses what it says are exiled Uighur separatist groups such as the East Turkestan Islamic Movement (ETIM) and the Turkestan Islamic Party (TIP) as being behind terrorism.
But overseas experts doubt the strength of the groups and their links to global terrorism, with some arguing China exaggerates the threat to justify tough security measures in Xinjiang.
