BBC reporter leaves China, says 'too risky to carry on'
Threats from Chinese authorities had "intensified" in recent months, he added.
At least 18 foreign correspondents were expelled by China last year, during a tit-for-tat row with the US that decimated the international press presence in the country.
Press freedom groups say the space for foreign reporters to operate in China is increasingly tightly-controlled, with journalists followed on the streets, suffering harassment online and refused visas.
"The BBC has faced a full-on propaganda attack not just aimed at the organisation itself but at me personally across multiple Communist Party-controlled platforms," said Sudworth, who will continue to work as China correspondent from Taiwan.
"We face threats of legal action, as well as massive surveillance now, obstruction and intimidation, whenever and wherever we try to film," he added, reporting that he had even been "followed by plainclothes police" during his departure from China.
In recent weeks, Chinese state media and officials have repeatedly attacked Sudworth for his reporting on alleged forced labour practices targeting Uyghur Muslim minorities in Xinjiang's cotton industry in particular.
The BBC also confirmed Sudworth's relocation after state media tabloid Global Times reported Wednesday he was "hiding" in Taiwan.
"John's work has exposed truths the Chinese authorities did not want the world to know," the broadcaster said in a statement on Twitter.
Xinjiang authorities said mid-March that Sudworth was the target of a civil lawsuit for producing "fake news" about the region.
But she denied the government had been behind the move to sue him and instead admonished Sudworth for leaving in a hurry and not clearing his name.
"Why did he run away? What does this show?" she said.
The Foreign Correspondents' Club of China, an unofficial advocacy organisation for foreign media operating in China, said Sudworth "forms one of an ever-larger number of journalists driven out of China by unacceptable harassment."
It added that he had been kept on "a series of short visas, variously lasting one, three and six months," putting pressure on his ability to raise his young family.
The club noted that attacks on Sudworth and the BBC escalated after the British broadcasting regulator revoked the license of Chinese state TV channel CGTN in February.