Taiwan's d a shot in the arm for the gay rights movement in Asia, but it is likely to be many years before China approves similar measures, amid deep-rooted opposition in some quarters.
Until 2001, China listed homosexuality as a mental disorder, but it is not illegal to be gay. Many large cities have thriving gay scenes, although gay men and women still face a lot of family pressure to get married and have children.
Wednesday's decision, the first such ruling in Asia, cements Taiwan's position as a beacon of liberalism in the region, and could prompt legal action by activists in Thailand, home to one of Southeast Asia's most vibrant lesbian, gay, bisexual and transgender communities.
Mainstream Chinese media either ignored the decision by Taiwan's constitutional court, or focused on the island's few protesters against it. The decision had "caused controversy", the state-run Xinhua news agency said.
China sees Taiwan as a wayward province to be brought under Beijing's control by force if necessary, and considers its people to be Chinese citizens. Proudly democratic Taiwan has shown no interest in being ruled by China.
But it is only a matter of time before China approves same-sex marriage, the English version of the Global Times, published by the official People's Daily, said.
"The ruling proves that same-sex marriage is acceptable in Chinese culture, and is likely for the Chinese mainland to legalize gay marriage within a decade," Li Yinhe, a prominent sexologist at the Chinese Academy of Social Sciences who has backed proposals to legalize gay marriage, told the paper.
But the far more widely read Chinese version of the paper was silent on how the decision might affect China.
Despite muted government reaction, the news drew millions of views and many broadly supportive comments on Weibo, China's answer to Twitter.
"This is the broad trend of the times. It doesn't hurt anybody else," Li Tingting, a gender equality and gay rights activist, told Reuters.
Taiwan's decision would help promote the same-sex marriage issue in China, said Li, who was detained in 2015 for trying to fight sexual harassment and goes by the pseudonym Li Maizi.
"But the problem is society is too conservative," she added. "Many people have never had any contact with anyone gay."
As if underscoring that view, a Chinese academic denounced the news on the site Confucian Web, urging parents in Taiwan to move to China to safeguard children from catching AIDS.
Wei Xiaogang, who works on gay rights and gender issues at the Beijing Gender Health Education Institute, said he felt reaction in China had been generally positive.
"It raises the visibility of equal marriage in China, and if more places in Asia approve this, China will feel like it won't want to be left behind," Wei told Reuters, though he could not predict how long the change might take.
Chinese literature and history are rich in description of relatively liberal attitudes to homosexuality in imperial times, but the Communist revolution of 1949 ushered in more prudish attitudes towards sex.
Beginning in the late 1970s, however, China eased up on such strictures as it embarked upon landmark economic reforms.
Still, though there are a handful of openly gay celebrities, no Chinese politicians will acknowledge being gay in public, unlike in Western countries.
Trying to gauge the extent of support for gay rights in China is difficult as no proper polls are published, said Sun Wenlin, whose landmark case last year seeking permission to marry his boyfriend was rejected by a Chinese court.
By Ben Blanchard | BEIJING